Try this for starters then http://www.stonefisk.com/doc-arc/def_man/ThermoGuard_Tdi_Tuning_Rev.2.pdf It'll tell you how to improve the performance of your tdi without spending any money. Of course if there are other problems causing lack of power you'll need to sort them out first. A basic good service with all new filters is a good starting point.Did search and found nothing??
What happens is that the detonation from the easy start creates a much bigger pressure rise in the chamber than normal, this hammers over the edges of the pistons gripping the top ring, and then when the motor warms up the ring cant go anywhere so it breaks lowering the compression, and the engine is then 'addicted' to easy start as it wont go without it.
That AA man was either a tosser or was fooked off with yer motor.