Loss of power after CAM belt replaced

Hi, seeking some advise on an issue I have as the mechanics at the garage seem to be stuck on solving the issue. To make it short cam belt snapped while driving at an average of 40 mph had it taken into garage and replaced only now it is running again but very slow on acceleration. Now turbos working maybe only slightly working not sure but seems to be extremely slow when driving. The guys in the garage are convinced the valves remain straight and not bent after the belt snap due to the car starting and running first time. Each time no hesitation any suggestions on what may of occurred or has been overseen that may solve this issue and bring the acceleration back to life? New belt and pulleys apparently have been replaced correctly apparently, but they seem to be stuck on the issue why the throttle is so slow when the turbo is still actually working. Any help at all will be fantastic.