[srad34]

As others have said, the AOS sounds like the culprit. Mine failed and the vacuum was not abnormal either.
The easiest test as said is the disconnect the pipe from the top of the AOS to the inlet manifold, if this has oil in it, the AOS is failing and getting into the inlet, oiling plugs etc = starting issues.

Too much oil will eventually end up back in the inlet when the AOS fails.

It will still smoke for a few miles after AOS replacement due to burning oil residue in the rest of the system.

Regarding the garage you use, I would strongly recommend you finding an independent specialist or teach yourself as some folk think we all have blank cheque books and although an not overly complex engine, they do have a fair few issues and can be easy to mis-diagnose!