Credit One Bank Changed Due Date Las Vegas NV

Received a credit card thru Credit One Bank and everything was okay until they realized I was going to pay my bill on time. Set up a due date with them for the 21st of each month thru their web site and had the payment automatically sent thru my bank to be paid 2 days before the due date. Got my bill on Feb. 13th DUE Feb. 17th. When I called to find out when and who had changed my due date I was hung up on, not once but two times of course this was after I asked to speak to a supervisor because they told me it's a $10 fee to pay my bill!  Total scam. If anyone out there gets a pre approval letter from them, no matter how hard up you are RUN.