Have you tried alternative streams from another provider? The BBC service is generally pretty solid. www.bbc.co.uk/radio. Also the BBC services don't have to go very far to arrive at Plusnet (peered connection) so there is less reliance on other providers.
Could be the rise of demand at your exchange (across all ISP's). Its more likely that the effects of contention will be felt with the bulk upgrades going on as well as new signups.