Thanks Ldnn1, it was interesting to read that. I suspect that what helped in the TLV-AMM-JFK case was that Avios had been taken, therefore technically a contract existed.

I wonder where I would stand - I requested a change, BA offered it to me for a certain price, I accepted and gave card details for payment (and emailed myself a reservation confirmation from BA.com showing 'confirmed' on all sectors). Is the contract executed when I provide the payment details, or when BA act on them?