Terrible service at toyzone Centurion lifestyle centre

I purchased a Lego set for my son as a birthday present. he opened the set and started building it. Unfortunately, there was a piece missing in the set. I took it back to Toyzone for a replacement or a gift voucher and was informed that they cannot help in any way and that I must contact Lego directly who will then make arrangements to replace the missing piece. Very disappointed with this terrible service. My son is very disappointed and must wait for a piece to enjoy his toy. I went onto the Lego website and cannot get help there as well as there is something wrong with the links. So I have spent a lot of money and time and there is no way forward.