Cancellation fee after inform no cancelation fee

Hi I will never recommended cat track even to my family as friend i was with them for over 36 month so last month i decided to trade in my vehicle and o contact the call center and spoke to account department and there inform me that im on a month to month contract and don't have a cancelation fee to pay to cancell my contract she just confirmed with me to gift car track 21 days notice as i have and now i receive email with over due letter or my account

I WILL NEVER RECOMMENDED THEM TO ANY ONE