Firstly, welcome to FT and to the BA forum where your thread now sits, sorry it is in such circumstances.

Whilst I don’t think BA are legally liable here, persistence often yields a small reward and I would try writing back to BA via the reply link on their email in through the complaint form on BA.com. You may be able to try alternative mediation and there are good details of how to do this in the EC261 thread available in the BA forum dashboard (:sticky near the top of the forum). unfortunately, EC261 is not applicable in this case, but there is still useful information in that thread.

Ultimately, this depends on how much you wish to spend time pursuing this, Any ‘compensation’ is unlikely to be significant and you may just think that BA didn’t manage the situation well and choose another airline in the future.