I had a booking I made after lockdown to return back to the UK from Santander in May, that Brittany ended up cancelling, so we chose to travel via France and the tunnel, Brittany offered us a voucher instead of a refund.
I emailed them saying this was not acceptable, but got another response saying that they would not refund, lucky for me I had paid for the booking with my Nationwide credit card, so I made a claim through them, took about 4 weeks, but I received my money back from the credit card company, I have had it drummed into me from my pal who is a barrister to always use my credit card for anything we purchase over £100.00, this is the first time I have ever needed to use this option.