I spoke to BAEC and apparently it looks like it will take 6 weeks for both cash and Avios, because for some reason it did not get automatically processed by the system (he said the system was probably down at the time) and has to be done manually.

A warning for those of you with tight cash or Avios balances - be careful because it can leave you short, although Avios should normally come back sooner.

BA5E wait 6 weeks and follow up because it apparently can take up to 6 weeks for the cash component to be refunded, although Avios should normally go back immediately (but not always).