Hi

I have an Audi A6 2.5Tdi Quattro and recently paid £1000 for service including brake pads and 2 timing belts. When we picked up the car it was making a clackety noise from the engine (sorry for the description). Then it wouldn't start. 2 weeks later we are told the valve in the engine stuck; worn hydraulic lifter and now 18 out of the 24 lifters sheared? This was after the garage test driving it; gunning it saying it was the turbo and then saying nothing was wrong.

Question - can replacing the timing belt affect the hydraulic lifters and damage them if it's not done correctly?

Thanks