Contract Cancellation - Bad Client Service from Vodacom

My contract expired on the 29 of December 2020. I phoned Vodacom on Wednesday the 27th January 2021 (for the third time in January 2021) to inform them I want my contract cancelled and moved to prepaid. I was advised that the cancellation will happen by the 31st of January 2021. The cancellation did not happen and we are now in February 2021 and I am expected to make an expensive payment for an unwanted month-to-month contract. Vodacom is very quick to contact you about upgrades but drag their feet when it comes to cancellation wanted by clients. CAN SOMEONE AT VODACOM EXCUTE MY REQUEST URGENTLY?