I've found the customer service in Sweatshop to be very good across a number of London branches and far superior to that of Runners Need. I had no idea they were owned by Sports Direct, particularly since the website boasts Sweatshop as "the UK’s favourite as well as the largest specialist independent running retailer ". They have also recently started charging for delivery to store, which was the only way to shop there considering how little stock their stores carry. I'll be shopping elsewhere from now on.
I have been using the Karrimor Urban 30 for running to work one/twice a week for about a year. As a serial cheap-skate I don't have enough good pairs of jeans so I take my clothes in the bag every day. It's a great size for clothes plus lunch but in the winter when you might want another layer it's not really big enough. The zips are fine but the lining between the sections has ripped so it's one big space inside now - not an issue for me.
However, I find the chest and waist straps rub my tshirts quite badly to the point of ruining them. I have the straps as tight as they go else it all moves around too much, I think the straps would be too loose for anyone smaller (5ft11, 70kg). It's also useless when it rains.
I tried another smaller bag in the summer but the straps were wider and irritated my neck where it rubbed.
For the bargain price its great. I've been looking at the Deuter speedlight and racepack as alternatives but I expect they would rub and wear away my tshirts in the same way. Probably isn't a solution to that.