A VCDS scan is something that you can do yourself, if you are handy with a Windows laptop, but, first check the "Free Scan Register" on here, to maybe find a member not too far away, who will scan it for you.
The scan will tell you why you are getting an occasional EML light, as every time this, and any other fault conditions occur, they are logged in the ECU, and remain there, until cleared, by VCDS (or other VAG specific scan tools).
It'll tell you if you have a misfire, and if so, which cylinder.
No doubt there is something to be sorted, but without a scan report, you, and the garage, can only guess.
Good luck, an FSI, in good fettle, is a wonderful thing.
Mac.
PS: It's a good idea to share the scan report here.