Vodacom doubled charge me and they dont want to refund me

Vodacom has charged me twice i paid R318.20 at a vodacom shop since my contract was in erears and that consultant **** to me said i can't pay at a shop need to be debited his name is lindokuhle and after i paid on the 18th of july tgey debited that same amount on the 25th july when i call vodacom they are saying i did not not pay and it does show on my bank statement they even extended the contract without my permission, again they said i can cancel the contract if i lost my job now they are saying i cant untill the contract expires and i have prove that m no longer working but still they wanna charge me for canceling