Incompetence service by MTN.

On the 30th July I went to MTN store in Menlyn to Pay my account used my card and paid then on 15th this Month I get notification that money went out same store I was in last time and that is same amount so quickly ran to the store and explained to them even produced bank statement they checked on my profile but the money doesn't reflect only the one 30th reflects then they advised me to Go to the bank which I did and they told me they need a letter for them to Reverse the money and I have waiting for a letter or way forward till this day nothing is fixed and I still haven't got my money back and this shows so much negligence and *********** services please I Just want my money back.