Failure to deliver service now handing me over to debtors

I've been handed over to debtors only because I reversed my debit orders after Netstar kept on debiting my account even after I cancelled their services.

This has been a nightmare since beginning, they didn't install the unit on time it took months for them to have their accounts manager call me persuading me to agree and apologising for their bad service in which I gave them a second chance then it began by them debiting me amounts which we never agreed on I contacted their call centre but was sent from one person to another no one could explain, was promised they won't bill me next coming months as my account was in credit guess what they still billed me I then requested for cancellations nothing happened hence I decided to reverse and stop the debit orders. That's when they started calling me saying I owe them now they have handed me over ruining my credit score and saying I should pay 3k+ for what I don't know because I've only been with them for a month, the unit I bought it via the dealer all they had to do was render service so no services were rendered so no pay.

I'm not willing to pay the outstanding I just want my name cleared simple, I owe you nothing