Mtn charging for wrong contract that i didnt even apply for

I have contract that i got in Aug, upgrade. I took the Made for me XS bundle for R299...My mtn App says i have the Made for me S bundle at R399 p/m eventhough the contract paper says Made for me XS @R299 ...currently the bill is running at R730 and i dont use the data or minutes or sms's because im home on wifi...theres another phone on this contract but its for R150/160 p/m.. These contracts are paid every month by debit order, Yesterday evening the bill was running at R716..this is ridiculous Mtn has a fight coming their way