Timing belt skipped

Servus has a really big problem. My dad changed the timing belt with my Audi 80 Coupe MKB: ABK. Everything according to regulations. He ran really bad at the beginning, so I gave him to the VAG to adjust the ignition (doesn’t go with the ignition light gun;-). Then he ran perfectly. I then drove 2 weeks without problems and with full power. I then let him run in the stand for a time. At the same time, when the fan jumped powerfully started , to clack. Short jump – car turned off After that tried to start again, which did not work. He ran only with the help of the starter and that very cumbersome. So I once took off the timing belt cover and put it on OT. When it went crazy it cracked a few times. The fact was, the timing belt was skipped by 4 teeth. Everything went back on OT and ZaCK the cart. Although bad as right, but it ran. So I went back to the VAG and asked the what the car was doing with the ignition. and if he could set me the ignition again. Date made on Friday to leave the car, all great. Until then the car ran well to moderately depending on the temperature. The hotter she ran the better, the colder she ran. On Friday I left the car and they said I could pick it up later. Well, that’s how it was. Unfortunately not, the mechanic called me that the timing belt was already half down again and he picks it up for me to check everything. Further phone call later he said that he could not find a fault (all wheels fixed on the shafts; tensioning roller bolts straight, tensioning roller and timing belt tension). He said he would order me everything including dampers, since he didn’t know what that could be… So my question to you is, what do you mean or had already jema and such a problem and do I need all this new? Thanks in advance Winkiger