Vodacom contract

I had a contract with Vodacom which expired in 2020 during covid level 5. I phoned their call center several times asking for cancellation with no help.

After numerous calls I was advice to go to one of their store which is Southgate mall Their assistant in Southgate promised to do the necessary to cancel the contract.

To my surprised I got a call from a certain law firm allegedly send by vodacom informing that my account has been handed to them and suggesting that I make arrangment as to how am I going to pay, and further recieved sms threatening that if I don't pay the money will be garnished from my salary