Unprofessional, rude and stinking attitude by cashiers

I have never been so humilated in my whoe life. I purchased a phone at MRP, then received voucher for R250, when i went to Hammanlsraal Kopanong branch to use that voucher, ur cashiers were so rude, didnt know how to use the voucher and accused me of *****, saying my signature doesn't look the same, therefore demanded ID, next thing they laughed about it. Honestly that shop must just close, only 1 cashier is working and u find that queue is very very long, stuff is very rude, yoh hai.