bug fixing

I have purchased a freelance script similar to gaf. Except for the advertising feature everything seems to work fine. When i try to sign up as advertiser the script won't recognize the confirmation code. As admin i can not add or delete advertising users. I am pretty sure that the script is buggy but I am no programmer.. If anybody here is able to fix the script i'd be willing to pay.. if the script can't be fixed i obviously don't want to pay anything. FTP access and the sourcecode will be made available.