VW polo 1.4cl 98reg. Had new cam belt and alternator belt fitted, now has really low compression... Help!!!?

The alternator belt went, and when I got it repaired it ran lumpy with low compression. Had cam belt replaced with new, and throttle body reset, and not lumpy now, but compression really low. Head gasket ok, but car is really slow to pick up speed, and seems to stop accelerating at about 3600revs. Any ideas? I have a very tight budget after the work already done, but cannot drive this slowly, it's too painful! .....help!!