Pay it, or call them up and ask them if this is a final bill or if they are still waiting on supplements. You can wait until the bill is final or you can pay as it comes in, you'll end up owing the same amount either way.
BTW, it doesn't matter whether they actually got the car repaired or not. They are owed the cost of repairs.
BTW, it doesn't matter whether they actually got the car repaired or not. They are owed the cost of repairs.