iPhone 4S will not charge or turn off

Hi,

My iPhone 4S will not charge, connect to a computer or turn off. When I try to turn it off, the spinning circle comes up for a few seconds then it turns back on again.

I've tried a hard reset but I don't want to have to do a factory reset without backing up all my information - which I'm not sure I can because I can't connect to my Mac. :/

I am booked in with the Apple store for this Friday - but I'm working away from home at the moment and I really need my iPhone working.

Does anyone have any advice how I can get it to charge please? :)