Unfortunately this somewhat makes sense... Now, if her account has been closed, then this is a design flaw. But if it's still there - just hasn't been used in ages - then this sanity-check makes sense to prevent fraud.
Software Gore
A community for posting software malfunctions
Deliberately bad software or bad design is not software gore, it must be something unintentional
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It's perfectly reasonable for a couple to have their own accounts plus a joint account.
True. I guess given that the way I've always done it here (one contacts the bank directly to open a new joint account) rather than trying to add a second person to an existing account, I hadn't considered that approach. Still, I can somewhat understand the rationale behind this design.
also mobile numbers are a bad identity vector. Some keep theirs for decades, others may change them several times a year every year.
Having a rationale is good, contradicting real use-cases is not so much. I met validations that are constructed without a lot of cases in mind lots of times. My favourite one was assuming the zip code is always 5–6 numbers, which is not always the case in length and in some countries it's not numbers at all, and that was a logistical company that was supposed to know things well
You can’t have a joint credit card account. It has to be in one person’s name.
I've had exactly the same problem a while ago with Barclaycard, had to phone them.