Billing

In August I order a month to month internet on the mtn website I paid R816 which included pro-rata, a few days later after the wifi was delivered they debited another R816 from my bank account of which I contacted MTN to enquire as to why I was being billed for the 2nd time. I was advised that the refund would take 15 working days, I than contacted my bank to assist me with the refund of the 2nd R816 that was debited. I than contacted mtn to inform them that the bank managed to reverse the 2nd debit the person that assisted me confirmed that it was their system error and it has been corrected the outstanding amount was only R11 for the reversed debit order. My ongoing monthly payment is R429 however on the 4th September I received an invoice stating the amount due was R1203 and this amount was debited I then contacted them to find out what was going on I was told the payments I made in August do not appear on their side. I have even sent my bank statement to them but there is still no assistance whenever I call they all say different stories. I wouldn't recommend this service provider to anyone.