Looks like Plus Net might be the best option. I've got to get a MAC key from the currently supplier (which could be a lengthy process knowing their procedures), but then it should be fairly simple.
I use PlusNet Broadband Your Way Pro (£20 approx, gaming) option now.
Only 2 complaints I have had in the past 4 years - getting speed increase set correctly, going over my "unlimited" allowance.
Ping seems pretty good as is connection.
Were nice enough to send me a letter rather than cut me off when credit card expired and gave me 2 weeks grace.
Owned by BT now btw, but haven't seen much difference since they were taken over.
G'luck with MAC - can't new ISP help in someway?
Oh and for Saint (courtesy of PlusNet):
"A MAC key (Migration Authorisation Code) is a code which any Internet Service Provider can give a customer to let them move their broadband to a different provider. Each MAC key is different and includes 4 letters, 7 numbers (sometimes up to 9), a forward slash, 2 letters, 2 numbers and 1 letter. So a typical MAC key would look like this: BBIP87654321/AB12C"