Debited and account handed over to collections for a canceled contract

I canceled a cellphone contract while I was still in the 10 days cool off period, I never used the phone. The courier collected it...My account was debited, I reversed my money and I called the sales department and they told me they haven't received the phone in their warehouse. They then handed over the account to collections...I have called and emailed the last response I got was "we are aware and are sorting it out" it hasn't been sorted till today, it's been 1 year.