I cancelled an Avios 2 for 1 booking earlier this week via the call centre as I had spotted 2 CW seats on a different route I wanted.
Agent made sure the Avios and Amex 2 for 1 voucher were back in my account and visible to me before ending the call. Was advised the taxes/charges would take up to 30 days to refund to my account. No sign of them yet.