It's ok, it was getting a bit stabby but the whole thing was off as soon as I got to my car to go home. I don't think I could have pulled the wire out without major bra surgery unfortunately - although if I hadn't been about to go home anyway I probably would have resorted to that.
Ah bugger! I've never actually snapped one, just had that slow extrusion of one side out through a tiny gap, a millimetre at a time until my boob is being uncomfortably prodded.