ShippingAddressPage.cs

public partial class ShippingAddressPage
{
    private readonly IWebDriver driver;
    private readonly string url = @"http://www.amazon.com/shippingPage";

    public ShippingAddressPage(IWebDriver browser)
    {
        this.driver = browser;
        PageFactory.InitElements(browser, this);
    }

    // some other actions

    private void FillAddressInfoInternal(ClientPurchaseInfo clientInfo)
    {
        this.Country.SelectByText(clientInfo.Country);
        this.FullName.SendKeys(clientInfo.FullName);
        this.Address.SendKeys(clientInfo.Address);
        this.City.SendKeys(clientInfo.City);
        this.Zip.SendKeys(clientInfo?.Zip ?? string.Empty);
        this.Phone.SendKeys(clientInfo?.Phone ?? string.Empty);
        this.Vat.SendKeys(clientInfo?.Vat ?? string.Empty);
    }
}