Product: Vehicle loan or lease

Bmo has recently acquired my loan from Bank of the West on my XXXX  wheel. I went online to set up my account due to it being a new company I had to do some verification and get everything set up. I than proceeded to set up my online payments. I pay my fifth wheel every XXXX weeks religiously. I do this to save on interest and pay down my loan quicker. I set up the online bill payment and when I did, it was XX/XX/XXXX. The system would not allow me to pay my bill that day, it kept pushing it to XX/XX/XXXX which I found strange. It was only about XXXX that day so no way it was the next business day, I finally gave up and set the online payment for XX/XX/XXXX in the amount of {$250.00}. I made the payment re-occurring for every XXXX weeks. Today I happened to get on BMO 's website to check on my account, to see that I was issued credit for the payment on XX/XX/XXXX! I set this payment to come out on XX/XX/XXXX and they gave me credit for XX/XX/XXXX. I called and I spoke with XXXX representatives. I explained to them I pay my bill every XXXX weeks, the interest is roughly {$120.00} and the remaining goes to principle. I informed them that because they waited 5 days to give me credit for my payment that I now payed {$170.00} in interest! They tried to inform me that because it was an auto debit that it takes XXXX days to process. I was dumbfounded, I had never been with a company who does not give you credit for the day you set the payment for. He suggested to me that I pay a few days earlier so it can be credited for the day I wanted. I asked what the point of a due date is if you cant pay on that day and get credit for that day?? I told him that he is informing me that if I pay on my due date, they are processing it XXXX days later and now not only am I paying additional interest, I can have a late fee as well?! HOW IS THAT LEGAL! The one rep informed me the {$170.00} I accrued on the payment was interest from XX/XX/XXXX ( the last time I paid ) XXXX with a per diem of {$8.00}. I asked her to do the math in the calculator and she came up with {$120.00} not {$170.00} in which she responded " let me look into this again '' This company is doing very shady things with consumers money. I work in the personal loan/ auto finance industry. I know exactly how daily interest works! This company is out to take consumers money any way they can now that their indirect auto business is shutting down!! People who have perfect payment histories and pay every XXXX weeks are now being penalized and have NO option to make a payment and get credit for the same day. They have no branches in MD so its not like I can walk in and hand them cash money. When I asked if there was any way I could make a payment and receive credit for the same day, low and behold I was told NO!!! So your telling me that there is absolutely no way I can pay my bill and receive credit for that same day. Again, How is this legal?! He suggested I call on the day I want to pay and make the payment over the phone, he also informed me there is no guarantee that I would get credit same day for that either, that usually takes a few days to process. This company needs to be shut down for unlawful business and soon before they take all their consumers money! I cant imagine how many of their customers don't even know this is happening!