ahhhhhhhhhhhhh wish i hadnt started doing this

[Matt]

attempted to do the rear discs etc today, had to stop when i realised i couldnt get the caliper carrier bolts out, so decided to put it all back together and wait till next weekend so i can get some more bolts from VW.
anyway, put the handbrake release spring back on and the ****ing bolt that holds the other end of the spring sheared off, and half of it is stuck inside the caliper.

what do i do next? theres no thread visible but the bolt is about 2mm from the surface of the hole i i havent got anything to grip.