If only they answered the radio when you call them.
I tried a couple of weeks ago to use them for the first time. Actually gave it a few more calls than the prescribed three I should have before I gave up (wanted to give them a chance) and even called Headcorn to check that I'd written the frequency down correctly, which I had.
When I landed, an Instructor and another pilot said that they'd both tried to use them earlier in the week with no success.
I tried.