Making me pay double for delivery to same address

Placed order online to send flowers and chocolates to my wife, I have a R100 discount voucher to use from my FNB credit card. On check out I did see that I am paying double delivery charges even though its to the same address. I called NetFlorist and they gave me a voucher code to redeem the one delivery charge. But once I entered this code I couldnt use my R100 voucher as you can only use 1 voucher per order. I then called them again and the lady just basically told me either they cant help me. I need to make use of another service. I then demanded to talk to a supervisor, but no one was available and I was told that they can issue a refund for me but it can take more than a week for the refund. This is unacceptable... The service was terrible and I will never make use of you guys.