After you've glued it use a soldering iron to melt both half together. Get a paper clip and make into a Z shape and burn it in to the 2 half's to make a staple.
On a 2010,150 roadsport you have 6 relay the same plus a larger hazard one in the middle. Cant you use one of the 6 just to try.and the fuses under your missing relay should be 15,5,7.5,do your hazard lights work.
On a 2010 sigma the top radiator pipe is one piece, and routed at the side of the alternator, not above it. Yours could leak in 2 places, one above a belt and one above alternator plug. That looks like a 3 year drip to me.
Don't remove the pipe,just take the pads out and press the brakes and the piston will push out ,rebuild while in situ. plenty of YouTube videos about it,