MTN southgate terrible service

Hi, i would like to express my disappointment with MTN southgate next to checkers, their manager is John, on friday i went there to fix the error they made as i instructed them for my debit to be collected on 25th of every month but they didnt do that instead im being debited on the 1st of every month and there is no money by then in my account, so when i was there i sat there for about 20 minutes and the shop was practically empty , at the front all the tills were empty its 3 of them, on the couches on the side there 3 mtn employees helping 2 customers, when 1 guy was done i went to him and he rudely said to me he didnt call me i should wait to be called, i told him that i was since here for 20 minutes no one assisted me, 1 mtn lady came from the back and she assisted the lady that came after me cause it looked like she knew her, she didn't even border to ask who came first she just assisted her friend, and when i complained they looked at me like i was crazy no sorry no nothing even from their manager John, when i told him about my debit order problem he said i must call 135 i told him i did, then he gave me some email address i told him im at mtn store and i expect them to resolve my issue as it was caused by them, im totally dissapointed with their service