Hi,
Sorry for your bad experience, we will take your comments as important feedback and will do our best to change our system to make it more friendly.
We developed account locking because we had an increasing number of long term unpaid activations. We thought some users might be away for a long time and could not purchase credits, so we gave a month with several notification emails. But there were several users who didn't pay purposely and after blocking their accounts they paid back all the debts. To deal with this issue we developed lock system that would lock the account after a month of unpaid credits and automatically convert the next sale into credits to pay the debt. After that the account would return to normal state.
Apparently our activation/credit system have flaws and currently we are working so that the payments would be splitted during transactions. We will get rid of the locking as soon as we integrate new payment system.
Regarding the existing tiered activation, we also have been thinking about changing it to simple percentage. What do you think, would that be better option for you?