Couple more data points:
1) Avios booking for return flights. Flights cancelled by BA. Called up on 8 Apr to request a refund. Refund is showing on credit card statement today, but with a posting date of 9 Apr.
2) Cash booking for a car hire. Called up on 9 Apr to request a refund due to the flights having been cancelled. Refund is showing on credit card statement today, but with a posting date of 11 Apr.
Wait time was not more than 30mins for either call.