I'm in need of some advice regarding an exhaust brake if anyone can help?

short story is, got a 7.5 tonne daf recovery truck, broke down one day due to the exhaust brake sticking on, fitter came out, smacked it with a lump hammer (as you do) which released it and told me to carry on, a defect report was handed in when i got back to the yard but rather than fix the problem the answer has been to disconnect the bloody thing!

now i'm unsure how this stands on a legallity side of things, if said vehicle was to get pulled by vosa how would they look at it? if it was involved in an accident what would the view be on it? basically i'm trying to cover my own arse here as it's always the drivers resposility etc.

thanks in advance for any help.