Contract paid in full, account debited again

Since 29 May 2015 I have seen payments to Vodacom going off on my account.I have no Vodacom contract at present.From December 2013 the contract I had with Vodacom, was paid off by ABB South Africa (Pty) Ltd. They (ABB) transferred the number to MTN since then.I have tried to phone Vodacom numerous times to find out how this is possible and all what had happened is to put me through from one department to another, without having anyone assisting me on the problem I have.I went to Vodacom Woodmead branch and they informed me that Vodacom does not have proof that my account was paid off and therefore the deductions that have followed. The question which I then asked was: were they then happy for a year and 5 months not to have proof of this by not deducting from my account, mind boggling hey?MTN then said I must get the proof from the company who paid the contract in full from Vodacom. They also advised me to phone cancellations at Vodacom *** where a guy Pascal told me to phone ***. This number were one of the four numbers on a previous attempt which was told to call, without results.I have submitted the proof of payment this morning.