2018 International U-Joint failure

I am working for a mobile mechanic and we went on one the other day started at1pm.
I pull up first and as I'm getting his info and details I call my seasoned mechanic. He broke his yolk at the transmission the driveshaft had spun so much it had sheared the head of the bolts off at the second U-Joint almost completely and busted his exhaust. We replaced front yolk,U-Joint,Strap & bolts, Hanger carriage at 2nd U-Joint and put new straps n bolts on second U-Joint. Informed him when he got home take it to his regular mechanic and have the drive shaft replaced. After hitting everything it did it was probably damaged, but we didn't see any cracks stopping him from going 3 hours to home. After getting that back in, he still couldn't build air. He had hit his air inlet into the rear of transmission bending the bolts up cracking one side of the threads. By this time After locating parts getting them installing them it was 9pm. I said I'm not sure I can do anything until morning and that's probably an order part. But let me see if I can get you home. I red silicone the broke thred bolt hole and put the two bolts back in just hand tight. Then took 2 hose clamps went around both holes securing it and tightened a little. Let sit for 20 minutes and said ok either she's gonna build air and or were waiting on a part tomorrow. She built air,he was headed home.
Apparently I was off 2 or 3 splines on setting the timing on the yolks from first U-joint to the 2-one.
A strap bolts broke on the second u- joint( we did not replace this,just new strap n bolts), and everything I installed is ok. However the 2nd u- joint is separating. He's claiming I installed wrong. I asked him to take his drive shaft to get tested and let me know and we'll go from there. International said 2 or 3 splines out will not matter,but his drive shaft bouncing everywhere will, do I refund this guy or make him get the drive shaft tested first.