Did you find out exactly what they suspect is wrong with the trim rams?
There's something like 7 parts within each trim ram. The motor is about $600 new.
For the repair to cost 3000 pounds, they've got to be replacing the entire tilt/trim assembly. To mandate that, the tilt/trim frame/housing would have to be toast, which would imply lack of electrolysis protection, which in turn would raise questions to me about other parts that are suffering from corrosion/electrolysis issues.