CREDIT ACCEPTANCE CORPORATION Harassment although payment was already made, Internet

A problem with the payment.  I wonder. I recently bought a vehicle and financed through credit acceptance, due to self employment (with years of documentation) and a good credit score. Banks don't like self employed unless you are a corporation.  I happen to be an educator who teaches and tutors online to college students who mostly don't want to take the time to open their books. However, as many local colleges not hiring or now requiring Phd for Associate degree programs, I am an independent contractor doing what I do best, only in another forum.
 
It's bad enough that with a decent credit score I have to go through a company like this.  My first payment was due on 22nd. I paid on 17th at the dealership, because paperwork was not at finance company yet. It's the 24th and Credit Acceptance says they do not have my payment. Dealership claims they "mailed it" when I questioned them today.  I was not told they would mail it.  I assumed that in this day and age of technology, the dealership would credit an account and link to or transfer funds to Credit Acceptance.  MY bad for assuming.

However, my contract also did not state that Credit Acceptance has a very limited structure of accepting payments.  I do think this kind of information should be disclosed in a contract.  Honestly.

If I had known the dealership had to mail the payment, would have paid the money through western union (though very reluctantly).  They will not take my debit card as it is not one of their preferred banks. What's up with that? Oh really. Everyone else I know, including nearly every bank in the country, would accept any valid credit or debit card.  So, I can either mistrust the dealership or the Credit Acceptance.

 I have no idea if my first payment will be "found" or if my vehicle will get repo'd, as they said they would turn off the beeping GPS today and did not. After reading all the reports I am really, really scared at this point. I will not only have lost the vehicle I traded in, but my cash down payment as well. I will also be out the money I paid on my first payment.  Worste of all, my decent credit score will be ruined because of something beyond my control.

Exactly how do you justify doing business in this manner? I am angry enough right now over this scam to call the AG office.  This is outright scam. Yes, I never use that word, but this time I am. How do I know the payment not sitting at Credit Acceptance. If my payment was mailed on sat. 18th or Monday 2oth, they would have received it by now.  Is this a way to get money from people then just leave them hanging?

At this point I have no way of knowing whether the dealership or CA is at fault? No way of knowing. 

I am setting up my bank account for automatic draft, but after reading reports that they did not draft from other customers accounts, how can I be sure this is a better method?

I hope you see my dilemma.  If not for my own experience, I may have a hard time believing other customers, but at this point.....

Get a copy of your history of payments from Credit Acceptance and compare their history with your record of payments. It sounds like they may not have applied one or more of your payments to your account - otherwise they would not be calling you in advance of your due date. It is best to start now so you can get them to correct their records if necessary.