billing post contract termination

My name is Happy - Ive had a contract with vodacome for 2 yrs- I went to the store during the peak of the pendemic to advise my intentions of not renewing the contract - I was given a number to call by the consultant at Mall of the south - I have contacted vodacom in May 2020 and to My suprise Im being billed. The call center consultant mentioned that the contract will terminate end June and there wont be any further debit orders- however the amount owed is pilling from me reversing the debit order. Vodacom has very poor service and basically they are not doing their jobs.