A and C,
Much of your complaint seems to be with the CAA. So why don't you title the thred CAA money pit...........because as you say, they are the ones charging the large sums of money and making a profit.
The instructions for continued airworthiness has been arround for decades. If you never came across it before then it says alot about the UK system.
Cessna when they used cessna branded radios decades ago inlcuded the info in the maintenance manuals as a matter of course.
If you wanted to put in a King set then you had to not only modify the flight manual but of course also the maintenance information etc etc.
Aircraft move round a bit and your aircraft with the new DME could be in Italy next week. No LAMS/P there and if you have not produced the required info for the DME then there is a hole in the maintenance information.
Once again I say...........nothing new there.
Regards,
DFC