As departments, yes. As companies, they used to be, not sure about now. Virgin Mobile (and Virgin companies in general, the actual ones) tended to have a reputation for good customer service, nthell isn't really a Virgin company but rather bought rights to the name (and may have bought over Virgin Mobile - I'm not sure)
---------- Post added at 04:34 ---------- Previous post was at 04:33 ----------
Anyways, I'd be curious what Sitefinder had to say about your local masts -
http://www.sitefinder.ofcom.org.uk/ Bung in your postcode and see what it comes up with as the nearest.