Need help with my jail system.

So I got a special system for my bans and it works this way:

You break laws on my server, and depending on the grade, you'll get in one of the 5 jails.

Jail 1 = bad language
Jail 5 = Extreme hacking, dupe or something gamebreaking

When you are in a jail, you get 3 doors. 1 for each option. The options are:
1. Pay your way out
2. Pay 50% and get 50% ban
3. Full ban for x amount of time.

Now to the problem. I have commandblocks to give people ban when they go through doors, but they can't take the money if the player doesn't have enough. But the player can still walk through like, nothing happended. So basicly, you'll just go through the 1. door with 1 $ and lose no money, but still get out of jail.

I've been thinking of a fix, but can't seem to get the right plugin. I want people to pay money every time they enter a region and if they don't have enough money, they can't enter that region.
The region of course, would start from the door, and all the way to the pressureplate which unjails you.

Sorry for my bad english and thank you for reading this