I accepted a Spirit Airlines Credit Card and when they didn't send me a bill by mail they charged me a late fee. I complained to them then the same thing happened the next month.
I have since canceled the card but they continue to charge me with late fees. I have no intention of paying any charges that appear on this card.
In addition I signed up for one of their specials and found that Shoppers discount has been charging me $9.00 per month ever since.
Beware of signing up for any Spirit Airline promotion that they might offer at the airport or elseware.