I always use their Tesco Pay+ app you don’t need to user Clubcard and payment card as it is all together in the app. This may explain why I have never had the problem.
As usual I got my refund automatically today, as others have said it doesn’t happen with every transaction I looked when it last happened and it was over 2 months ago for a 60p chocolate bar.
I typically find they automatically refund the money a few days later at some obscure time of the night.
I think in future I’m going to use my credit card just to avoid the hassle and overdrawn issues because I have all my money in pots and only withdraw when I’m about to pay.
It’s happened to me three times, but not recently the last being a few months ago. Monzo should be pressing MasterCard who should be getting heavy with Tesco over it. On this forum I often read reports of it happening, and with most Monzo users not being members here how frequently does it really happen?