in this case, are you a general contractor?

if you are, then, are your workers your subcontractor or just your workers?

here's a general situation:

if you are gc, if owner doesn't pay you in full, you don't have to pay them in full.
if they are not subcontractor, they are your workers, you have to pay them in full regardless of whether you are paid in full.

contract and payment:

all shall be agreed before work starts. if your contract includes labor and equipment, you should provide. owner is not responsible fot repairing your truck. or get the parts.

any changes in scope of work or pricing should be discussed and agreed before work starts. if your subcontractor decided to do without your knowledge, you
may not need to pay them. if they are your workers, they can't make yhe decisions for you.

it looks like you can't control your workers/subcontractor, then it's a lesson to learn for the future.

if you want to be a gc, learn to control your guys (if you can't control the owner).

if you are not gc, their dispute is their bad luck starting with a car break down that they are liable to fix themselves. not your business.