it's not easy... but yeah Ford should be able to help you, but I doubt it will be a cheap exercise.

The TSC is based on wheel rotation using the ABS sensors. I can't see that you would have a calibration issue after changing the brakes. I've got the same set up (322mm front with upgraded 328mm rear). I'd say it's more likely the ABS sensor was damaged or dislodged during the install.

Just a guess though - someone else may have direct experience with the issue.

So... it turns out the DSC issue was not with the brakes at all but with the throttle body, which was coincidentally cleaned at the same time the brakes were installed. The clue came when the CEL also turned on a day after the DSC first started playing up and the car started rough idling. Guys at Dyno-mite were very quick to sort it out, car & brakes are working perfectly now 

what did they actually do to fix it? if the throttle body was cleaned, that doesn't usually cause anything like what you said, but OK...

Think they checked if the sensor was fouled or not and then they reflashed the ECM. The throttle body on mine was particularly dirty and as I understand (correct me if I clearly don't understand) the transition of it going from being putrid to spotless was too much for the computer to re-adjust for.

unless it was tuned while the throttle body was significantly compromised, cleaning it wouldn't make it do that... but ok, all good... as long as your problem is sorted.