TAP AWARD DENIED NOW I'M IN DEBT HELP!!!!

I received a letter about a year ago stating my tap award has been denied now I owe an outstanding balance of $2,675. They claim I failed to reply to them in a timely manner which I had no idea about. Due to the fact that I moved I received this notice weeks later. Both tap and the university I attended are giving me the run around no one is helping me nor giving me some type of Insight. I wrote an appeal letter to NY Higher Education Service. Months passed by I have not heard back from them. I finally contacted them back and they told me they denied my letter. Now I received a letter from a collection agency with a larger amount of an outstanding balance and I don’t know what to do anymore. I don’t mind paying them but at least tell me why and is there anything that I can do so I would not have to pay?