98 Ford Escort Timing belt?

Alright my escort zx2 is in the shop for the third time in a week. (definitely glad I have a warranty) The timing belt has shredded each time. The first time, apparently the tentioner was only half there. Second time, apparently it was defective belt. I guess I can accept those two. But this is not even a week later (not even a day later) to have the belt fixed again. I have been told by everyone I'm very lucky to have no engine damage thus far.
any idea what it could be? Could there be another underlying problem?

It depends on how fast the engine was turning when the timing belt broke as during idle speeds the belt may have done minor damage to the engine. What if at highway speeds when the engine was turning around 2k RPM's as once the belt broke as the valves hung open as you hear vicious bangs and realized there was piston to valve contact. After neglecting to have the timing belt changed at manufacture's specifications to save funds as you could be spending thousands on a new engine. As the US has a lemon law as you give mechanics three chances to fix the problem before you submit a case.

The mechanics have not noticed the cause of the damage, they are just replacing parts. A belt should be changed at 75,000 miles. Some of them go 150,000 miles, but it's a terrible risk. The idler pulley AND the tensioner pulley should be replaced AND the belt. You may have cause to use the "lemon law" in your favor. After three attempts to fix the same problem, your car is officially a lemon, and you are entitled to a remedy. It could be a new car for you. Look into it.