I have a problem and need some legal advice

I have a problem and need some legal advice. I bought a spa at the state fair in late August of 2010 . They would not take a credit card for the full amount and I did not have a check with me so they said they would give me 6 months same as cash. So I bought the spa and when the bill came it was 29.00 more than our contract said I would have to pay. So I only paid the amount on our contract. I did call G.E. Money Bank and ask about the 29.00 and they told me that it must have been a fee the spa company had put on the bill. So for the next month or so we tried calling the spa company but their phone was not answered or we got a message that it was no longer in service. So we decided to go a head and pay the 29.00 just to make sure it was paid before the 6 months was up as I have perfect credit and I did not want a mark on it. Well I went to refi my rental house and the G E Bank reported it being 30 days late and it is on my credit report. I called G E Money bank yesterday and they told me it was their charge not the spa's and that I had to have made a payment . They did not tell me what the 29.00 was for , I did not agree to any charge and I did not sign for any charge. They said they would take the charge off , I told them we already sent the payment for the 29.00 and asked them to remove it from my credit report . They said they could not do that. It is 2:30 in the morning and I am so mad and sick about it I can't sleep. I want to do something to fix this. I believe what they have done is very wrong and I want justice. It is just not fair. Can any one help , I need it fixed fast.