Cell Phone contract

I have taken out a contract in 2021, within a month the phone started to give problems, it suddenly went dead while i'm on the phone, then I have to restart it again, after some research, i have found that the prepaid price of the handset was only R1500 while the sales lady told me it was R7500, I phoned blue label connect to cancel my contract, one of the team leaders said that they would have to listen to the voice recordings, after I received no feedback, I phoned in again, spoke to the team leader again, she confirmed that I received misleading information and that the contract would be cancelled, blue label connect cancelled the debit order and arrange for a courier to pick up the handset, now after 2 years I hear from a debt collector that I owe Blue Label Connect over R7000, this is absolutely absurd, now everytime I have to follow up on the matter, they just make promises to sort the matter out.