After about 8h of hard work, today I finished cleaning, fixing and reassembling the #saeco coffee machine I use on holydays. The boiler had something like 3mm of limescale that had to be scraped using a sharp knife and sanding paper. No, limescale remover didn't do anything at all. I changed all main seals and the shower filter for 15 euros.
Preventing something from going to the bin is very hard work.