Originally Posted by
Tootall33
Do I risk losing my Avios and taxes refund and not getting anything from BA for what I spent in El Al if I don’t accept the refund from BA?
The idea is that you lose the Avios and taxes. The point is BA replaces your BA ticket with the El Al ticket, or here covers the reimbursement. If you ask or voluntarily accept a refund that is game over, BA has to give either a refund or a rerouting, not both.
However moving from Economy to Business won't be part of any EC261 claim, you have to come up with a price representing the economy fare by some reasonable way.