New battery for 355

[stuh]

My battery has been on the way out for some time, and has finally died completely. In an ideal world i would get Verdi to replace it, but as a) they are always booked out for weeks b) i don't have the time to take it there anyway, can anyone advise of somehwere in beds/bucks/herts that they would trust to replace it on short notice, ideally whilst i wait? I'm guessing as it's a wheel off job that your average kwik-fit is not a good idea?