Agreed Refund Never Given - Wrongfully Handed Over

ADT Security wrongfully debited my account with a debit order after the contract had been transferred to the new occupier of the property. The new owner also paid subscription. I reversed the debit order as it was no longer my responsibility. ADT thought it a great idea to hand the matter over to Debtsource to collect. I paid Debtsource in order not to have my good name and credit rating damaged, although not due by me. I still however continued the fight for this wrongful debt. Eventually during November 2015 ADT and Debtsource acknowledged that they acted incorrectly and that I did not owe anything. I was sent an apology letter with the commitment that I would be refunded within a couple of days. Now 4 months later I have yet to see any form of refund from ADT. Good thing I moved my security needs away from them. Would probably still be waiting for them to respond to an emergency for the last 4 months if the service level received thus far(or rather lack of service) is anything to go by. I would strongly advise any person considering to deal with them to rather approach any other player in the security industry.