Edgars - YOU operate a*********!

I got an sms from Edgars "spend R800.00 and receive R100.00 off" which I did yesterday at East Rand Mall, and at the till point the cashier and her supervisor refused to use my voucher as a pair of socks I bought was marked down. Edgars try and get us to the store to do purchases under false pretence. I will not by anything again, and will close my account soonest. Bad attitude from staff members