End contract. Renewed without my permission

I had a extra dafa bundle and unfortunately my son lost his phone. Therefore had to wait for contract to end. Vodacom shop bloemfontein told me early last year that contract end Aug 2021. When I visited the shop again they said that the contract was renewed May 2021. I did not give any permission as I did not have a phone anymore. I phoned several times to explain and requisted proof. No response. Last month I received bad debt letter. This is not acceptable. Who can assist