using (var proxy = new somenamespace.UserOrgHierarchyServiceInterfaceClient(binding, new EndpointAddress(host + "somewsdl.blah")))
        {
            proxy.ClientCredentials.UserName.UserName = username;
            proxy.ClientCredentials.UserName.Password = password;
            var getDevicesParametersType = new somenamespace.organizationQueryParametersType();
            int itemsCount = RequestWithCustomHeader(a => Convert.ToInt32(
                proxy.getOrganizationCount(
                    new somenamespace.getOrganizationCountRequestType
                    {
                        queryParams = getDevicesParametersType
                    }).responseData?.count), proxy);
            if (itemsCount == 0)
                Console.WriteLine("No organization");
            else
            {
                Console.WriteLine("Items count: {0}", itemsCount);
                var totalTasks = (itemsCount - 1) / size + 1;
                var progress = new TimerProgress(totalTasks, itemsCount);
                using (var tokenSource = new CancellationTokenSource())
                {
                    var cancellationToken = tokenSource.Token;
                    try
                    {
                        CreateTimerTask(progress, cancellationToken);
                        var organizationParentsList = new List<OrganizationParents>();
                        var errorAction = CreateErrorAction(targetPath);
                        var tasks = Enumerable.Range(1, totalTasks)
                            .Select(page =>
                                Task.Factory.StartNew(() =>
                                {
                                    progress.initiatedTask++;

                                    var result = Retry(() => RequestWithCustomHeader(b => proxy.getOrganizationsQuery(
                                        new somenamespace.getOrganizationsQueryRequestType
                                        {
                                            batchSize = size.ToString(),
                                            pageNumber = page.ToString(),
                                            queryParams = getDevicesParametersType,
                                        }), proxy), RETRY_LIMIT);
                                    ...
                                    process with "result"
                                    ...
                                })
                                .ContinueWith(errorAction, page, TaskContinuationOptions.OnlyOnFaulted)
                                .ContinueWith(t => progress.completedTask++)
                                ).ToArray();

                        Console.WriteLine("Tasks: {0}", tasks.Length);
                        Task.WaitAll(tasks);
                        tokenSource.Cancel();
                    }
                    catch (AggregateException ex)
                    {

                    }
                    catch
                    {
                        throw;
                    }
                }

            }


            Console.WriteLine("Press any key to continue");
        }

    /* definition for RequestWithHeader() */
    private static T RequestWithCustomHeader<T, S>(Func<ClientBase<S>, T> func, ClientBase<S> proxy) where S : class
    {
        using (new OperationContextScope(proxy.InnerChannel))
        {
            var httpRequestProperty = new HttpRequestMessageProperty();
            UserNamePasswordClientCredential userName = proxy.ClientCredentials.UserName;
            httpRequestProperty.Headers[HttpRequestHeader.Authorization] = "Basic " + Convert.ToBase64String(Encoding.ASCII.GetBytes(userName.UserName + ":" + userName.Password));
            OperationContext.Current.OutgoingMessageProperties[HttpRequestMessageProperty.Name] = httpRequestProperty;
            return func(proxy);
        }
    }