Bad Service mtn south africa

Wrong Billing. I have a wifi contract with mtn for R350 which I have religiously honored each month. To my surprise on the first of March they suspended my services despite payment having gone through. I have sent numerous emails to get to understand why they say I am in arrears of R465 whereas my contract is for R350 which is up to date but all in vain. Their whatsapp platform is equally useless as it only gives options which are irrelevant. I have requested they call me to rectify their error but still in vain, this has greatly inconvienced me and my family. Bad service from MTN south Africa