I'm in a similar situation. Got diverted to DUB and then just left to sort out getting home to MAN.
I paid 235 Euros for an Aer Lingus flight.
BA refused to pay out, and said I need to go to my travel insurance.
I'm still contemplating Small Claims Court. I don't care about the 235 Euros, it's just the crap way we were treated. So, even if I lose, it still means some BA dogsbody has to travel to court and waste a few hours.
Cheers,
Rick