Help please???

I was called by one of the Global Travel Alliance people two years ago, where they stated that I have won a all exclusive holiday and that I only need to come and speak to the consultant. I went there and the consultant has explained the whole package for me and it really sounded good for me at that stage. He has asked me for my credit card, where I told him that my card isn't working. He told me that it would be 100% and that I only needed to send in my signed documents to activate my account. A few days after that( within a week after seeing the consultant) I phoned them and told them that I cant afford it, as my work condition has changed. The lady over the phone told me that there isn't an account on my name and that it wont be activated. I have forgotten about this and out of the blue GTA phoned me at the end of last year and told me that I owed them over the R8000. The guy that phoned me, Jimmy, said that I needed to cancel it in writing and that if I want to cancel my account I need to pay a 50% of the outstanding account. I want to know why didn't they phone me after 2 or 3 months that my account has been overdue? Normally when your account is overdue for 1 month the people starts to phone you, but not GTA!!! Now they want to give me over to the debt collection department and this will have an effect on my credit score!!! This is complete bull****!!!