I'm pretty sure that Aegean will contact you regarding this change, especially as you say this happened yesterday. I've had award booking flight changes, and they always contact me. Don't panic, you've still got lots of time.
You'll definitely have the option to cancel for a full refund, but I'd ask them to try and find another solution (i.e. rebook with another carrier).
I didn't even realise Eurowings had Business Class!