Here's the test details
http://www.motuk.co.uk/manual/mc_contents.htm The plate is a non test item and you cannot be failed for it being too small. It doesn't even need to be present.
If they fail you for it, ask to see the relevant section in the testers handbook (Which they are required to have). When they cannot show it, get them to re-write the paperwork as a pass.
Then report them
