Extremely poor service and authorized debit

Trying to cancel my line as Accelerit is trying to debit my account without authorization. Had a 6 months once of contract and has being trying to cancel and get the line released from March 2023 with no luck. I had to pay upfront to qualify for the deal. They cannot provide the Sales recording nor have they cancelled the line. They send 2 invoice with different amounts and still cannot tell me what's going on. The agents promise to feedback however it's just a waste. The management email is of no help either. They continually request the invoices, and nothing happens after. You cannot get hold of them telephonically and when you do, the line drop after you explain the issuse.