I talked to staff about this. I don't blame them and it doesn't astound me. I have dealt with this sort of problem, and it *isn't* simple.
They swtiched banks *twice* in the last few years, because they have had trouble getting a bank who will process payments correctly. Their banks have repeatedly been misprocessing and misallocating payments. IMO, they probably should have taken the payment processing in-house and hired a staffer, but they keep having banks offer to handle it for them...
They also switched the IT backend on the membership database. That was expensive but totally worth it. It actually went well and the new system is WAY better. But they're now cleaning up the mess from the transition.
The previous database was such a mess that I had SEVEN separate membership records, and they had to manually merge them after the transition to the new database. (Luckily they can actually do those manual merges in a matter of minutes, so call them up.)
I strongly suspect that's what happened to the original poster -- I bet you're getting letters under different membership numbers. Call them up and have the memberships merged.
Jim Matthews was complaining about the disastrous state of the membership database he had inherited way back at the Chicago meeting in 2017, and at that time they hadn't started replacing it. It is *not* trivial to replace such computer systems and transition them, it's always a multi-year nightmare. They seem to be in the home stretch now, after 3 years of work, which is about right in my experience. The existence of an old system actually adds multiple years to the schedule; starting from scratch would be quicker, but you can't just throw out everyone's memberships and start over.
Consider how long it's taking Amtrak to replace ARROW (it's been over 20 years of work so far). Building a new reservations system from scratch takes less time, but you can't do that, you have to transition the old reservations across...