I had three flights from EDI to JFK, booked for 1st/15th April. When BA finally cancelled the flights I went on the website and was only offered a voucher.
Called the Newcastle call centre and, after an hour on hold, got hold of a very nice lady who told me that a voucher was the only option. I told her that I was legally entitled to a refund as they can't fulfil the contract - she put me on hold to speak to a supervisor, came back 10 minutes later and said they would process a refund.
It took around three weeks for the money to hit my account, and I was relieved when it did.
I honestly don't think the call centre agent I was talking to was lying, or deliberately trying to leave me on hold to see if I would go away - she seemed genuinely unsure of what the options were, which seems craxy.
So all came through but only after a lot of persistence.