VCNA knows all about the throttle unit problems and chances are good that if your service manager/writer contacts his rep, VCNA will decide to help out. I see that happen often. You originally had the problem under warranty so they can't deny that you tryed to have it fixed before.
IMHO, trying to clean a throttle unit is nothing more than a complete waste of time, for both you and the tech, even though I've heard some VCNA people suggest that as an idea to "try first". The throttle units I've removed, none looked all THAT dirty and usually when they go bad (causing a code), the code says "internal fault" so it's an internal electrical fault. Volvo knows the unit has problems which is why it was re-designed for '02s on up.