I reported this earlier this month. It is not the 5th payment that causes lockup, it is the 4th. That doesn't mean you aren't allowed to do four payments, just that they lock the biller account after four, and let you know via email. - edited to add: all four of my payments made it through, and my email stated 7/1 as well, so it should be calendar, not rolling 30 days.
Last edited by WhiteRoom; Jun 22, 2014 at 1:16 pm
Reason: more info