I eventually got my refund from NA about 7 weeks later… may be worth noting that Monzo wasn’t aware that I was refunded and you need to contact them about closing the chargeback case.
Maybe worth a suggestion that Monzo places a search marker on the accounts that chargebacks are made to check for customer refunds? Or noting on the chargeback letter we get that should we be refunded to let Monzo know. Could save a lot of time on Monzo’s side!