RCS -Bad Service

Bad Customer Service.I settled my loan in this month, i phoned to confirm if the funds were received and was assured that my account was settled and i even received a paid up letter. I received a bill more than a week later saying i still have balance .I called customer service they told me its not settled I asked how can it be if i have a paid up letter i was asked to forward them the letter and they never got back to me i feel completely ****** !