Served detainer warrant, is there any chance i can win in court?

I just moved into my apartment on 6/11/15, I was served a detainer warrant on 7/21/15. When i signed my lease i was told by the leasing agent "after" I signed my lease that my prorated rent would not be due until 8-1-15. Which she wrote down on my receipt when I paid my deposit. (i currently still have the receipt). The lease says 7/1/15 but she said I would be fine if I paid by 8/1/15. They mailed me "one" late notice, never called, or emailed me. I would have been more than happy to pay but the only contact was through the mail which i checked after 7/15. I tried to pay at the office but they told me they had already turned my account over to an attorney. I really don't mind paying the rent it was just a mix up on the days due to what the leasing agent told me and wrote on my receipt.