I'd heard from a couple of people about an independent that opened last year called Bournemouth LR in Alder Hills, Poole.
I had my air con re-gassed on Sunday, by one of the big chains, I know that I shouldn't have gone there but was the only place open on a Sunday. They managed to over gas it, had 500g more than it should have done.
Took it to Bournemouth LR yesterday and I was very impressed, they have all the diagnostic equipment, air con machine etc and Tony and Lorna who run it are amiable people.
Would recommend them.