Mtn Billing Issues.

I upgraded my data contract in November and was charged and paid the Pro rata fee and again in December I have been charged the pro rata fee. I went to a Mtn Store on the 23nd to report it and was told it was an error and now the money has again been deducted from my account. You cannot phone Mtn from your Vodacom cellphone because when you choose the option to speak to an agent it keeps telling you invalid option pressed. I want this resolved please .My nr is ***.