what customer service????

Absolutely non-existant customer service! Extremely unprofessional & nowhere to be seen when something goes wrong. I had an account, used it regularly & paid well above the minimum payment amount each month. One particular month I paid my payment too early as the follwing day I got an email telling me I could view my statement online. I rang their customer 'service' department & explained I thought I had mad a payment on my account too early, they assured me they could see I'd made 2 payments within a month but that this was enough to cover the coming month balance. I said i could make a further payment there & then but they said there was no need. At the end of that month I then got a letter saying I had missed that months minimum payment & had been charged £12 late payment charge. I explained via phone the situation but in the end paid the whole balance off & asked for my account to be closed as I was so annoyed at how they handled it. After explaining via many emails their staff had advised me no extra payment was required I made a formal complaint. A manager was supposed to call me back twice, no call! I have also wrote to them demanding at least my £12 refunded, they haven't even replied!