Hopefully i can help..
What engine size/fuel type do you have?
Any unusual noises from the engine/exhaust system in regards ***** ***** noises etc?
Hi Robert, thanks for the reply, the engine size is 1.6. We haven't noticed anything untoward re noise levels.
Hi..there thanks for getting back..
Normally with any type of exhaust fumes leaking into the cabin is down to leak somewhere at the front of the exhaust system/manifold or gasket leak.egr gasket leak which i can see it being to be honest...The cat converter "if petrol" shouldnt cause this unless it was damaged/corroded allowing gases to escape...if a diesel engine 1.6d then the dpf normally doesnt cause this either,you may find a hot type smell under regeneration..they should recheck the joins/differentail pressure tubes/aswell as turbo unit connections,egr....the fact you had the clutch done and this problem arisen would suggest they have removed parts of either of the systems above and not sealed them back properly..thats my understanding without seeing it and the only real cause for exahsut fumes to enter the cabin... unless its fuel smell then that would have to be investigated for and should be easily spotted for wetness - they have to properly recheck the system is sealed properly at the joint/gaskets...rather then guess whats wrong at you expense..maybe get a second opinion and take you findings back to them..I do hope this helps