Audi A3 8v Throttle Actuator Control System Stuck Open

I have a 63 plate Audi A3 2.0 Diesel S-Line, the other day whilst driving home I noticed a flashing light on my dashboard, but everything seemed fine, no loss of power or anything. It turns out to be the Diesel glow plug warning light. It's the first time I have seen this warning, and it didn't happen again for a couple of days until today it came on again. I took it to a garage where they ran a scan and the error code that is given is P2111- Throttle Actuator Control System Stuck Open. They had a look and unfortunately it doesn't seem like an easy job to get the damn thing out and look it over. They phoned up for a genuine Audi replacement just to get a price and they quoted me £281 +VAT. And then 2.5 hours labour on top so I'm looking at bill of around £600!!!! FML!

Has anyone else had similar issues? And does that quote for the part sound about right? In all fairness the garage did say it might end up that I don't need to replace the part, they will strip it out and inspect to see if it just needs a clean or if any of the wiring needs replacing.

Thanks in advance
Gary