I had 2 BA holiday bookings for mid April and Early May, the sequence of my events is as follows.
I had only paid the deposits and + £200 on the later one (Amex avios bonus thing spend £100 I think).
As soon as the voucher thing was talked about I applied for vouchers for both.
The full payment due emails came for the April holiday which I ignored obviously and then had you can pay t-3 weeks instead.
Flight in May was cancelled so use contact form online to ask for a refund - after a few days a very nice chap emailed me and sorted it all out - refund in bank few days later.
Flight in April, which was overdue has also now been cancelled - emailed nice chap (as I had his email address), I did apologise and said he could tell me to "go away" if he wanted, but within 5 mins he emailed back saying he processed the refund.

Have to say in the scheme of things BA have done me good, I will be back if there is indeed anything to go back to!