Credit Union changed account number, now new checks are being denied everywhere
Hello, my mother is in a deadlock trying to figure out why she can't use her checks. Her credit union changed her account number and issued new checks. They were denied when she would try to use them. After the problem continued, the credit union tried closing that account and opening a new one, and these checks are also being denied. The credit union claims this is the first time this has happened which I do find hard to believe. They aren't offering any other solutions and my mother's been unable to get through to the services that clear the checks at the businesses she goes to to find out any other info.
Could anyone help us figure out what might be happening here, and what kind of solutions there are?
edit: thanks so much for all of your replies! I had to step out for a work call right after I posted so my apologies for my delayed responses. Working on them now!