public void saveData()
        {
            try
            {
                using (var context = new CarDealerDataContext())
                {
                    foreach (var c in customers)
                    {
                        var _c = new Persistent.DB.Customer();
                        bool flag = false;
                        if (c.Id == 0)
                        {
                            flag = true;
                            _c.Address = c.Address;
                            _c.Name = c.Name;
                            _c.Phone = c.Phone.ToString();
                            if (c is Domain.Customers.Private)
                            {
                                var p = (Domain.Customers.Private)c;
                                var _p = new Persistent.DB.Private();
                                _p.Age = p.Age;
                                _p.Sex = p.Sex.ToString();
                                _p.Customer = _c;
                            }
                            else if (c is Domain.Customers.Business)
                            {
                                var b = (Domain.Customers.Business)c;
                                var _b = new Persistent.DB.Business();
                                _b.CompanyName = b.CompanyName;
                                _b.Fax = b.Fax;
                                _b.SerialNumber = b.SerialNumber;
                                _b.Customer = _c;
                            }
                        }
                        else
                        {
                            _c = context.Customers.Single(_cu => _cu.CustomerId == c.Id);
                        }
                        if (c.Vehicles != null)
                        {
                            foreach (var v in c.Vehicles)
                            {
                                if (v.Id == 0)
                                {
                                    var _v = new Persistent.DB.Vehicle();
                                    _v.Brand = v.Brand;
                                    _v.Color = v.Color;
                                    _v.Model = v.Model;
                                    _v.Price = v.Price;
                                    _v.State = v.CarState.ToString();
                                    _v.Type = v.Type.ToString();
                                    _v.Customer = _c;
                                }
                            }
                        }
                        if (flag)
                        {
                            context.Customers.InsertOnSubmit(_c);
                        }
                    }
                    foreach (var v in vehicles)
                    {
                        if (!context.Vehicles.Any(_v => _v.VehicleId == v.Id))
                        {
                            var _v = new Persistent.DB.Vehicle();
                            _v.Brand = v.Brand;
                            _v.Color = v.Color;
                            _v.Model = v.Model;
                            _v.Price = v.Price;
                            _v.State = CarStates.Commision.ToString();
                            _v.Type = v.Type.ToString();
                            context.Vehicles.InsertOnSubmit(_v);
                        }
                    }
                    context.SubmitChanges();
                }
            }
            catch
            {
                // hahaha I've screwed sth up :((
            }
        }