Dissatisfaction with Vodacom....

I have been offered a promotional Laptop package in February 2023,I have had a contract with Vodacom since its inception, I took the offer as the consultant promised that the contract costs would remain the same and they assured me they would, after receiving my statement, to my amazement I was billed almost double, having received this information I returned the laptop, having sent numerous Emails to cancel the contract as I had advised I cannot afford the repayments, the last email was sent on the 8th March 2023,I am however still being billed for a laptop i have returned on the 3rd March 2023,it was couriered by RAM ref COL***5.I am extremely disappointed in Vodacom's service and unwillingness to assist as I am not prepared to pay for a Laptop that i do not have, can someone please assist in resolving this matter as the Vodacom branch in Fleurdal was not able to assist. And I phoned Vodacom Promotion Department as well and they said the can't end this contract before it is paid in full. Why must I pay for a Laptop that I don't have. Having been a contract user for so many years I expect better service please rectify urgently.