Wrongful debt of account

I had a Nashua Mobile cellphone contract and Nashua Mobile only informed me via sms a week before my account migrated to Altech Autopage that I was going to be migrated, but left no contact number where I could call them to cancel my contract with them. A week after the notice was issued I received a sms from Altech welcoming me to the team. Immediately I called them on the contact details provided and informed them on 19 November 2014 (ref A***) that I would like to cancel my contract on the date it was due to expire which was 28 December 2014. Altech Autopage Customer care consultant confirmed that it would be cancelled on that date. I then called the days approaching the cancellation date and I was informed that the information was on record. I was informed that I not be billed December however I was billed, when I called to find out why was billed I was informed that it was the last bill for the month. In January 2015 I was billed again and I was informed that it was for a handset. I called the customer care and was informed that the query would be sent to Accounts for the amount to be credited, that did not happen so had bank reverse amount. I was billed in Feb 2015.