Ally people are idiots. My boss just bought 4 new jeeps for the company when they had their 0% financing. All 4 payments are due the first week of each month, so I enter the information into Quickbooks for each account and it cuts one check for all of them.
Every single month they apply the check to only 1 account and then their collection's people start calling us on the other 3 accounts. I give them the 4 account numbers and tell them to fix it. Believe it or not their collections people tell me that it's not their problem, they just want to collect the money, they aren't in charge of how payments get applied.
So you know what I do? I give them our 4 account numbers and tell them to call our corporate office. (They have no idea they are actually speaking to the corporate office!) I give them the toll free number for Ally Customer Service!

It seems to work, because they get it fixed and don't bother us again...until the next month!
I've done everything, attached notes tell them to apply to all 4 accounts, etc. and they just seem to ignore it.