Contract Cancellation and My name handed over to debt collectors

Cellphone collect from me and I was refunded money blue label deducted onto my bank account. Now I recieved a call from some debt collector saying my account had been handed over to them by blue label. How is this possible. As I do not owe blue label a cent.

I am going to be blacklisted because of your incompetency.

What kind of a company are you and what kind of a system are you using.

I regret the day I requested for a contract with you.