For a minute I was trying to work out what Onto had to do with it, and why they'd be desperate, then I re-read and realised you're not talking about the subscription company (where we get Shell cards that work with Ionity).Onto the ‘only if desperate’ pile then
I had a brief chat the last time I used Ionity - a poor bloke who was trying to charge using a payment card, I think he was facing the old "chip + pin" problem that many card users face and had to resort to I think a third payment card before he could start charging. It was hard to communicate as he had a cochlear implant and I had trouble understanding him, I felt really bad for him and was very happy to see he got charging eventually.