account closed and now being charged for a new num

i have closed my account in January 2016 after paying it off in full. in February I get billed for R534.27 which was debited from my account. I have now received a statement telling me I will be billed at the end of March.<br> after going to gateway , I was told I have to call the call center because I am on a 3D system and then get transferred to all different departments that cant help. I have now been told that I must go make an affidavit stating that I don't know who's number they have decided to charge me for. why should I go sit in the police station to make an affidavit for their mistakes?<br> I will never use Vodacom again neither will I recommend them.