I need my 50% discount i was promised

On the 18th of december i got an sms from edgars with a 50% off code for my next purchase if i do a credit increase and its approved. I then took my ID account card 3 months bank statements to edgars promenade mall mitchells plain and it was sent through then a week later around christmas time i went to edgars canal walk to get my 50% discount but when the code was punched in i was told that its not working because the credit increase was probably not approved they then took me to the phone and called your credit department i think and i explained to them and was told that edgars promenade did not do it properly and my id number was not on the documents they sent through and i also did not sign something that i was supposed to sign then i was told to go back there and do it again, I then went back to edgars promenade with all my documents before new year and they told me they did do it right the first time they then sent it through again and the woman turned the screen towards me to show me they sent it she then told me to wait there for a few minutes she then called to ask if they got it then the person on the other side said they dont see the bank statements, the girl who helped me then told me they are just plain lazy on that side and that it is always an issue with then she then sent it again, then i got a call days later to ask what my expenses are and tell me it was approved now i want to use the 50% off code only to be told it expired at the end of december, please do something about this as i have done what i was supposed to do in december already and tried to do my purchase in canal walk and your *********** credit department staff blamed promenade mall staff and promenade mall staff blamed credit department for being lazy and i had to go back and forth with my documents and have it sent thrice and now i cant even use the discount, this is not my fault if your staff did their job right the first time i could have made my 50% purchase around christmas already I want my discount please rectify this my account number is ********** ********** 51