An unauthorised second debit order being taken from my account

I have been with MTN for years and have never had a problem with their service or the way in which they have debited my account.

I changed banks from Nedbank to FNB 3 months ago and have discovered for the last 2 months, that MTN has been debiting my account for a second time, with an unauthorised amount. My normal contract amount is R 317,02 but I am being debited a day later for another amount with different reference number for an amount of R 479!!! I ended up having to go to FNB and have this reversed.

I have not agreed to change the terms of my contract, have the same conditions and phone so nothing should have changed!

I have been trying to resolve this for a month now and I can't reach ANYONE via phone and the customer care team (via email) takes forever to get back to me and has me running in circles with no resolve- needless to say, it happened again at the beginning of May and they debited R 958 (to claw back the reversal I did through my bank from last month) and I am still waiting to hear from someone after escalating this numerous times- I am fuming!

I need to be contacted via phone URGENTLY to resolve this matter!!!!!!!!!!