Out of curiosity, which branch did you use ? I have used the Snappy Snaps on Bishopsgate a few times and they have been OK.
I used to use the Lomography store at Spitalfields but that closed a year ago, hence heading to Snappy Snaps for convenience. There is, I think, another shop near Soho, so could be worth a look.
Quite a few places you can send your rolls to via post, but never used these myself.