One of the pads fell out of my hayes nine caliper with the pin still attached is there anything I can do ?????

Was the little spring properly attached to the piston thingy?

the pin has broken off the caliper piston.

anyone know of any bodge's to hold the pad in ????

Time to fit a new piston.

"Time to fit a new piston"

can this be a diy job ?
cost ?

Piston + seal about £7, can be done diy if you're mechanically competent. Zip tie the other piston in place and pump the other out if you've not got compressd air, split caliper, clean bore and seal groove, lube piston+seal with silicone grease or brake fluid, re-assemble and bleed. Good idea to make sure it's clean before disassembly too.

I replaced my pistons, took a while but was easy enough

ah simple enough
Have done the same on my motorcycles