If you are "up for it", you could buy in a set of dust seals and calliper - piston seals, and get the piston out and see if you can polish it clean again. I've suffered a seizing rear calliper on a 2015 VW Polo a couple of years ago, which was a bit disappointing, due to wanting to get the car back running asap, I just bought a re-manufactured Pagid Lucas/TRW calliper via Halfords, then got round to buying in a couple of seal kits and some new aluminium fluid line sealing washers - I really should complete that job this year as if one side had ended up corroding its piston, then the other side must be doing the same thing! I've bought, maybe M16 nuts to act as spacers, so that I can secure the brake discs snuggly on the hub using either wheel bolts or other suitable bolts, so that I can check the discs for "run out". Grooved discs, I bought them for one car as it suffered "brake wash out" in winter, which was a bit scary and VW sorted that out with later models, but, I did end up finding the need to replace one axle set of ATE Power Discs just because corrosion had started to "range out" from each of the grooves probably due to that car only getting used once every 4 weeks in winter, as I was in a "car share" for commuting to work! That was a bit more than annoying.