just done exactly the same, Dumped 3 cos they are crap n gone pay as you go with Carphone Warehouse on union st,was with that one in arndale for years,went around a few places asking for a Bog Standard phone which you cannot have on contract, and got a nokia now with 02, same as my missus etc, had it 3 months now n well suited,think it cost about £20,check em out mate.
ps give yer notice in writing, or 3 will not accept.