Incorrect Billing

In April I ordered a microwave from Home Choice, it was delivered to me but unfortunately I had to send it back because it was faulty. I was then promised another 1 but delivery took centuries which resulted in me having to call and cancel the order. I was promised that the account will be credited within 48 hrs but this was not the case. I then called again and was told my query had been forwarded to their enquiries department and they would get back to me, this did not happen. I called again in was told my account would be cleared in 3 days and still a heavy balance remains. They are good in calling customers and reminding them about payment but they fail in attending to their customers enquiries. I've been nothing but a good customer ensuring my account is paid on time, and this is the thanks I get for my support? I am very unhappy and am taking my loyalty elsewhere.