Useless App - Cannot pay for goods

I have been trying to use the [URL Removed] app every time they send through a promo code for the app. It never works. The app must be the worst I have ever encountered, it is so buggy.<br> Today I tried to order an item using the 10% off code for the app. I got all the way to the end and I got the same problem where the credit card facility didn't work. They have had this same problem for months now and no one fixes it. I contacted the customer support and she said that she could cancel my order so I can try again. This doesn't work. I asked if I could give her my payment details to process but she told me this was not possible.<br> How can a company make it so difficult to buy from them, I have now given up and will take my business elsewhere.