What happens if you accidentally tap out with a different card?

Ugh, so you accidentally tapped out with the wrong card? Been there, done that, got the weirdly inflated bill to prove it! Let me tell you, it's not fun. I once did it – tapped out with my old student Oyster card instead of my new contactless, and the charge? Seriously astronomical. Felt like I'd funded a small country's bus system. Apparently, the system sees it as two separate, unfinished journeys. Two! Can you believe it? It's like, the system thinks I was cloning myself to travel or something.

So, yeah, using the wrong card means you get hit with the maximum fare on both cards. It's a double whammy, a transport-based punch to the gut. Not cool. Avoid it at all costs, seriously. It’s costly – that maxed-out fare is no joke – and super inconvenient. You have to deal with sorting out refunds, which is always a joyous experience, isn’t it? (Said no one ever.) Trust me on this one, check that card before you tap!