Refund request

I have been a client for over 15 years and yet this establishment has not learned how to treat their customer's fairly. i was double debit and every time i call to enquire i will be told the money has not reflected. i have tried to change banking details 4 months ago, till now they are debiting on the wrong account. i want my refund ASAP. Mind you everytime you need to request of a call back, i have done so everyday. its either the buzz or not call at all.