Difficulty in cancelling Telkom mobile contract

In May 2019 some time I agreed to get into a Telkom mobile contract from one of Telkom mobile sales agency and when the device was delivered to me and as i was in process of registering the sim card and all i found out that not everything was disclosed to me and i within 3 days of receiving the device i returned the device with everything it came with. I called the sales house if they would be facilitating the process of cancelling the contract with Telkom mobile on my behalf and i was advised that as soon as the device has been collected from me and delivered back to them they would cancel the contract, which didn't happen. I started receiving invoices from Telkom mobile i then took it upon myself to cancel the contract myself on the Telkom mobile website and i received reference numbers for both the two sim cards. Despite me doing a follow-up calls on numerous occasions regarding how far Telkom mobile is from cancelling. Instead i have to keep reversing Telkom mobile debit orders because they change their reference number everytime and i keep receiving an accumulated invoice from Telkom mobile monthly. I thought i would give Telkom mobile a second chance but i have come to a conclusion that Telkom mobile doesn't improve their service. I need to cancel this contract ASAP, please assist me?