Changing brake discs and pads

[Peteridd117]

today I tried fitting new front brake disc and pads, the right side I got on no problem but the left was a problem. The calliper pin/bolt won't go back in, I tried leaving the calliper off and inserting the pin/bolts but they won't even turn. I tried using the right side pin/bolts but they also wouldn't turn? The bolts look threaded (from the left side) and worn can someone help, thanks

[Peteridd117]

I have a seat ibiza 2013 fr if That helps

[Peteridd117]

There is threads missing on the bolt, it's the bolt that gets torqued off to about 30nm it sits on top and bottom of calliper goes through calliper and into a bracket?