I hear what you say @jamesallison That’s definitely an edge case that we’ve consciously decided to leave unsupported for now, I’m afraid.
When we started planning top up via card we even discarded increments of £50, the idea was to only accept multiples of £100 to keep the top up screen easy to read and ensure a fast flow.
Then, after a few more weeks of manual top ups, we realised that lots of people were topping up multiples of £50 and we decided to cover those cases too. And even more by giving multiples of £10 just when below £100.
I’m sure we’ll need to adjust things on that screen soon, we’ll keep your request on mind. Thanks!