Those that pull through will be stronger for the experience as they develop resistance over time. Sorry if you lose any of them. Coccidiosis is everywhere, every country, every back yard, so do not take it personally that they became ill; With restrictions SO tight on medications in your country, you're bound to lose birds to what would otherwise be easily treatable conditions. Coccidiosis usually doesn't rear its ugly head in a flock except in the young birds or in birds that are suffering from an unrelated illness, compromising their immune system.
Found this OLD posting for coccidiosis and Canada, and thought you might like to read it through; see if anything in it is helpful to you and your situation. https://www.backyardchickens.com/threads/corid-for-a-canadian.1209212/
