Boost Mobile Sprint, Nextel what exactly is a due date? Irvine, California

I have been a loyal Boost customer for about 18 months.  My payments are due on the 28th of each month and I have made each one as agreed.  At 1:43 am on the 28th of December my service was interrupted due to non payment.  My understanding was that payments were due on the due date.  I spoke with a decent customer service rep who admitted that there was some type of system wide billing problem that caused customers to have their service suspended prematurely.  He said that he had brought this to management's attention already but that the response that he received was that it was a systemic issue that could not be corrected and that he was told to offer me the option of changing my plan.  It may be a mere coincidence but I recently signed up for a new feature that reduces my monthly payment by $5 after 6 consecutive timely payments and the new plan would cancel that feature.  I do not believe that I have been singled out and that this has all the earmarks of a class action lawsuit.