Xml way

void Main() {
    var wb = LoadWorkbook(@"D:\Downloads\EU.xlsx");
    //  wb.DocumentSettings.Calculation.Mode = DevExpress.Spreadsheet.CalculationMode.Manual;
    //  wb.Worksheets["Output"].Range["A49:E70"].ExistingCells.Select(x => $"{Column.FromNumber(x.ColumnIndex + 1)}{x.RowIndex + 1} {x.Value.TextValue}".Dump()).ToArray();
    var doc = ProcessBlock(wb.Worksheets["Output"], 50, 1);
    doc.Dump();

    XmlReader reader = new XmlNodeReader(doc);
    var serializer = new XmlSerializer(typeof(Premium));
    Premium result = (Premium)serializer.Deserialize(reader);
    result.Dump();
    reader.Dispose();
}

XmlDocument ProcessBlock(Worksheet worksheet, int topRow, int leftColumn) {
    XmlDocument root = new XmlDocument();
    Func<String, XmlElement> createElement = elementName => root.CreateElement(elementName)
    var premium = root.AppendChild(createElement("Premium"));

    int row = topRow;
    while (true) {
        XmlElement element;
        int height;
        var value = worksheet[row, leftColumn].Value;

        if (value.IsEmpty) {
            break;
        } else {
            var text = value.TextValue.RemoveWhiteSpaces();
            if (text.EndsWith(CollectionSuffix)) {
                (element, height) = ParseToCollection(text, worksheet, row, leftColumn, createElement);
            } else if (text.EndsWith(TableSuffix)) {
                (element, height) = ParseToTable(text, worksheet, row, leftColumn, createElement);
            } else {
                element = ParseToSingleElement(worksheet, text, row, leftColumn, createElement);
                height = 1;
            }
        }
        premium.AppendChild(element);
        row += height + 1; // +1 for the empty row under the collection
    }
    return root;
}

XmlElement ParseToSingleElement(Worksheet worksheet, string elementName, int row, int leftColumn, Func<string, XmlElement> createElement) {
    var element = createElement(elementName);
    element.InnerText = worksheet[row, leftColumn + 1].Value.ToString();
    return element;
}

(XmlElement table, int tableHeight) ParseToTable(string tableName, Worksheet worksheet, int topRow, int leftColumn, Func<string, XmlElement> createElement) {
    var tableBodyRow = topRow + 1;
    var element = createElement(tableName);

    //get labels from the area under table header
    var labelsColumn = worksheet.Columns[leftColumn];
    List<string> labels = GetColumnValuesUntilEmpty(labelsColumn, tableBodyRow);

    //get element properties from the column to the right of lables
    var elementColumn = worksheet.Columns[leftColumn + 1];
    var properties = GetElementProperties(elementColumn, tableBodyRow, i => createElement(labels[i]));
    properties.ForEach(x => element.AppendChild(x));
    var totalTableHeight = properties.Count + 1; // +1 for the header of the table

    return (element, totalTableHeight);
}

(XmlElement collection, int collectionHeight) ParseToCollection(string collectionName, Worksheet worksheet, int topRow, int leftColumn, Func<string, XmlElement> createElement) {
    var elementNameLenght = collectionName.Length - CollectionSuffix.Length;
    var elementName = collectionName.Substring(0, elementNameLenght);

    // get collection elements from the area under the header of the collection
    var (elements, elementsHeight) = GetCollectionElements(elementName, worksheet, topRow + 1, leftColumn, createElement);

    var collectionRoot = createElement(collectionName);
    elements.ForEach(x => collectionRoot.AppendChild(x));
    var totalCollectionHeight = elementsHeight + 1; // +1 for the header of the collection

    return (collectionRoot, totalCollectionHeight);
}

(List<XmlElement>, int elementsHeight) GetCollectionElements(string elementName, Worksheet worksheet, int topRow, int leftColumn, Func<string, XmlElement> createElement) {
    List<XmlElement> elements = new List<XmlElement>();

    var labelsColumn = worksheet.Columns[leftColumn];
    List<string> labels = GetColumnValuesUntilEmpty(labelsColumn, topRow);

    // get collection elements from the area to the right of labels column
    for (int columnIndex = leftColumn + 1; ; columnIndex++) {
        var elementColumn = worksheet.Columns[columnIndex];

        var element = createElement(elementName);

        var properties = GetElementProperties(elementColumn, topRow, i => createElement(labels[i]));
        if (properties.Count != 0) {
            properties.ForEach(x => element.AppendChild(x));
            elements.Add(element);
        } else {
            //right edge of the collection reached
            break;
        }
    }
    return (elements, labels.Count);
}

List<XmlElement> GetElementProperties(DevExpress.Spreadsheet.Column column, int topRow, Func<int, XmlElement> createElement) {
    List<XmlElement> properties = new List<XmlElement>();

    var columnValues = GetColumnValuesUntilEmpty(column, topRow);
    for (int row = 0; row < columnValues.Count; row++) {
        var property = createElement(row);
        property.InnerText = columnValues[row].ToString();
        properties.Add(property);
    }
    return properties;
}

List<string> GetColumnValuesUntilEmpty(DevExpress.Spreadsheet.Column column, int topRow) {
    List<string> labels = new List<string>();

    for (int row = topRow; ; row++) {
        var value = column[row].Value;
        if (value.IsEmpty) {
            //bottom reached
            break;
        } else {
            labels.Add(value.ToString());
        }
    }
    return labels;
}