In version 0.0.2 there was a bug in the billing system. It basically caused it to not send out bills for the premium ALPHA services. This lead to members using resources which they are not paying for.
One of the fixes in 0.0.2:09 was to fix up the billing system; a part of that fix was to work on the backlog of unpaid bills. The backlog of bills is being sent out a 60 min interval. How many bills each member gets is varied according to how much free stuff he/she has used. Not paying a backlog bill has the unfortunate side effect of cancelling your membership.
There are basically two issues that stem from these bug fixes
1. Members that had kept a lot of server slots for later use and have not gotten bills for them are getting a huge backlog. The amounts can be quite high. There is little unfairness going on here, the price was known and you should have expected to get billed eventually.
2. Members that were honestly using their slots but didn’t have the chance to pay the bills at the right time (as they weren’t sent out) and were not logged in when the backlog was worked down and therefore didn’t have a chance to pay the bills, have gotten their slots cancelled. I agree that this is unfair but this is a case that is difficult to fix as new people have taken the opportunity to rent the slots.