That's really unfortunate - every sympathy with the situation and the level of frustration generated by the creaky BA customer care.

Assuming the phone bill was split into a small number of long calls on hold, claim for the two most expensive, which is allowed under right to care. With the EC261 compensation you shouldn't end up too much out of pocket, and also check the terms of your travel insurance.

I use Skype with Skype credit for calls when not in a free roaming destination, and the BA freephone numbers don't use credit up. It works very well. Also online chat and twitter is a reasonable way of communicating with BA. I guess another point is that you can get very proactive with BA but the outcome may not turn out all that different, at some point they're going to be in touch and get you home. If there are seats available then you will be put into them, so one strategy is just to wait it out. You don't need Avios availability on IRROPS, there may be a requirement to take a lower cabin class if you absolutely have to be back if there are only seats in economy, but you would qualify for downgrade compensation.