Forgot about the interest, they should still refund you in my opinion as they don’t offer swag any more or metal card price draws (which was later added to legacy, see below) 
But our current thinking is that once we’ve fully tested metal cards (hopefully towards the end of September) we’ll start running prize draws for all new customers who’ve bought the Supporter bundle and for all customers who’d signed up to Monzo Plus previously, but haven’t had a chance to switch to The Supporter.
From: We're rethinking Monzo Plus bundles (and some other updates!)