Mtn will rob u blind

I paid mtn 2 weeks ago nd then they go and take R823,32 from my account for wat, the contract is only R366 a month and I paid it in just this month ive paid well over R1000 and I emailed proof of payment this debicheck mandate is simply so these guys can take money as they please. I can't get hold of mtn via phone or email only on facebook messenger and they insist they will only refund me R366 but I paid R366 plus they took R823,32 I want this resolved today im so angry and upset so I'm short R823,32 because I've so far recieved no refund nd its R823,32 they must refund not the payment I made but wat they stole out of my account. Be careful mtn will rob u blind and just take ur money as they please