23 years a Vodacon customer that is billed after contract was canceled and expired

Good day from 2019/12/01 one of my sim cards expired and i phone in and cancel the contract as i have a nother contract that is 23 years old so if been calling for 11 Months now they only cancelled on 22 Of October 2020 they have been billing me on that simcard for 11 months now they failed to still get the call records to credit my account so this cause to put my account in arrears the simcard has been blocked 2 months befor it it expired i still paid my account so now they have blocked my line every time i call in they put the phone down in my ear this is unacceptable to get billed for a contract or sim that is not even on air they want me to upgrade on my number now and i told them they can cancel it as well and put it on a pay as you go as im not happy for the service of 23 years