Hello Jon and Welcome - My name is XXXXX XXXXX Im happy to help you -There are only a couple of reasons for this to happen - ie, to come back from a timing belt change - being quiet and underpowered...Either, the piping / wiring and so on to the turbo system has not been re connected or has been dislodged etc - meaning the turbo is not doing anything ... or, they have mis fitted the belt.. the latter is a very common issue with this engine.The former - with the turbo side of things is easily checked - I would think that they would have determined that by now - so I feel its more likely the timing belt issue. If the belt has been fitted out of time - and it only takes 1 tooth to be wrong - it wil be seriously under powered - ie, wouldn't pull the skin of a rice pudding is the saying... So if its like that - Im afraid they have to strip it all and check the set up.I have to say -its very easy for when this belt job on this vehicle is being done -its very easy for it to "slip" out of time - unnoticed by the fitter... ( experience of these ...sadly as well as knowledge of it as a common issue - ).. So they are going to have to strip the belt system to check it.Hopefully, thats all it is and they can re time it and all will be well-- but - if the belt was badly out of time, it can have caused damage to the engine - engine valves ...and that will cause driveability issues too. If the belt is re set p / re timed and its still not right - they will then have to investigate that side of things - a compression test on all cylinders would be the next step then..So given what you have outlined, those are the ways forward to progress on this for you now and get this sorted for you..Let me know how you get on - or if you need anything else at all...Kind Rgds - MIKE....Meantime..............Please do click on the "OK/ Excellent ratings" for me as that's how Im credited for helping you - Thank you in advance for that...You can and are most welcome to get back to me anytime you might need - clicking the OK ratings does not close you out at all..Rgds, MIKE.