I understand your way of view on this suggestion.
[Suggestion]:
Why don't we work with something like a criminal record?
You can buy an unban or unmute - whatever u want to buy - once in awhile and it cleans your record.
[Solution for the hackers]:
Whenever u get another punishment your previous punishment will be readded.
For example: U have a ban / mute, u buy an unban + unmute. *20 weeks later* u get a mute ,then ur ban + mute will be readded from the previous punishment.
*Aslo, don't make an unban/unmute 5 bucks or something. Make different prices - depends on what "crime" u have. For example: an unmute just because u flame is around 10$. A ban because u are hacking is around 20$.