Many thanks Nigel,
Probably not bought from a main dealer due to age of vehicle -?
I think what you have suffered from is cheapest repair option.
Although I understand where you are coming from in respect of ‘always fit in pairs’ ( discs and pads), I don’t necessarily think this is always necessary - proviso:- the disc surfaces are reasonably free from scoring, and will remain within thickness tolerance through the life of the new set of pads, and are not suffering from vibration on braking. The latter may actually be introduced on fitting new discs.
In your case, there is absolutely no doubt that the discs are totally shot, and your principle should have applied without question.
Perhaps you could let us know how you get on.
Kind regards,
Gareth.