the bobbins that hold the actual disc to the disc carrier failed
That's the one.
I don't have photos of the front i'm afraid.
But as said, the pistons have seized and the bobbins failed. (sorry, i'm not overly knowledgeable with this stuff)
So the pad in the photo (rear) has 3mm left on it. The rear brake always did nothing from the moment i got it. (hence why the pad is weird .. and that's why i asked the question of timescale and salt corrosion on a pad)
the front worked but the wheel was locking (had the bike on the centre stand and a mate held the back down and i couldn't move the front tyre)
The pads on the front are worn but not terrible, it's just the 6 pistons seized and the disc fucked..
They did the MOT and as my mechanic said, or suspects, they didn't check the bike over before it went or it wouldn't have been so low on oil / coolant + the brake situation.
But apart from that, do you guys think a pad would have worn in that way because of salt corrosion with 3mm left on it + the other damage?
Thanks for the all replies guys,