I must be careful what I say, or I could get into trouble...
I've been deeply messed around by avionics firms who don't do what they say, and don't deliver a fix when promised.
Stapleford, Southend, and certain airfields in Kent have failed the test.
One at Staverton, however, scored well - it was a lot cheaper to fly the aircraft over there for attention, than to try to get it done in the South East.