if you use the link below to download the costa app, you get 1 bean to start, then 5 more with your first purchase of a Costa hot drink. That’s halfway towards a free one.
I find this app particularly generous - I seem to have odd free coffees all the time for no reason (I had two free yesterday despite not having loads of beans) - certainly more rewarding than other apps I have.
swf3j.app.goo.gl/yM47H