you wanted a seal, and lots of responses were how to get the seals.... in an overhaul kit, probably because most caliper issues are to do with sticking pistons - which is often due to bore or piston damage leading to seal failure.
A mate with BMs often pulls his apart and finds corrosion, not surprising as its very common on bikes, I was looking at the fronts on mine this year, 7 pistons were like new, 1 had corrosion, damage.
If you have seal failure but all pistons are like new, it sounds to me like overly aggressive cleaning agents or left on too long