private void UpdateShippingOptionRate(PostBackModel model)
        {
            var shippingOptions =
                _workContext.CurrentCustomer.GetAttribute <List <ShippingOption> >(
                    SystemCustomerAttributeNames.OfferedShippingOptions, _storeContext.CurrentStore.Id);

            var shippingOption = _workContext.GetBpostShippingOption(_storeContext);

            if (shippingOption != null)
            {
                shippingOption.Rate = model.DeliveryMethodPriceTotalEuro;

                _genericAttributeService.SaveAttribute(
                    _workContext.CurrentCustomer,
                    SystemCustomerAttributeNames.OfferedShippingOptions,
                    shippingOptions,
                    _storeContext.CurrentStore.Id);

                _genericAttributeService.SaveAttribute(
                    _workContext.CurrentCustomer,
                    SystemCustomerAttributeNames.SelectedShippingOption,
                    shippingOption,
                    _storeContext.CurrentStore.Id);
            }
        }