Got Orange Broadband at the moment and it is a bit crap I'm afraid. You wont get 20mb, check the news, only about 1% of the country actually has the capability to get these speeds and there is a push by law makers to stop broadband providers quoting max speeds instead of average speeds which are much lower.
Customer service is okish, but in two years of having it have had to partake in at least six or seven 30 minute phone calls because the broadband has reset itself and wont work. Customer service are complete 'script readers' and are not experts in any way whatsoever.
I am pretty sure there are better providers out there...