You seem to misunderstand something, namely the conditions of the contract you make with British Airlines. You are not buying a ticket good for 9000 km long travel, planes are not priced like that, you are making a contract with BA at price point which ~30 years ago would've been absolutely impossible and in turn BA prescribes severe restrictions, as it is only fair. You can certainly buy a ticket where if say "jump", BA will only ask how high. This also has a price which I believe you would find, to use your word, indecent.

You are breaking your contract one sided and expecting the other side to do as you wish outside of said contract. Good luck.