I had a dumb one a couple weeks ago. We purchased a rental house in June; the mortgage has a credit line in conjunction with it — for whatever reason, the new mortgage came with an entirely new credit line (even though both are set up on our principal residence) and the old credit line was closed.
I decided I wanted to put our extra accumulated cash against the mortgage (allows for 15% prepayment during each year without penalty) but we don’t have a bank account with that bank. I used my same method as before, set up the LOC as a bill payment, paid it into a credit balance and asked the bank to transfer it over. Except, the money kept not showing up. After a few days, I realized I must have set up the bill payment wrong. ACK!! I remembered I’d had trouble finding the LOC account number, because all of the docs from the bank had the middle portion of the number xxxx’d out. I was relieved when I had come upon a letter showing the full number as I was going through the file, and (gleefully, yes, I am a nerd) set up the payments (multiple payments, because the amount exceeded the daily bill payment limit).
Turns out the letter had been the one notifying me that the old LOC account was closed. Of course this realization happened over a long weekend/bank holiday, so I still had to wait a few MORE days to have the bank find the money sitting on the old account, transfer it, and transfer again to the mortgage.
Overall, this might have cost $30-40 in foregone interest earning in savings/extra interest paid on the mortgage, so hardly devastating; but, oh, the shame! 😳