ACS INCORPORATED They've sent me hundreds of emails and claim they've attempted to contact me via phone, Internet

The company claims I owe them money but have not provided any details around what for?

This is in reference to your Account number 51-707410 with ACS in order to notify you that after making several calls to you on your phone number, we were not able to get hold of you. So the legal department of ACS has decided to mark this case as a flat refusal and press charges against you.
 
Your account with ACS is in Final Collections. According to our records, your outstanding balance is $841.45  Do revert back if you want to get rid of these legal consequences and make a payment arrangement within the next 48 hours or else the case will be downloaded against you.
 
As we have shared with you in previous letters, read your loan agreement; the next step is clearly defined. It could cost us both a great deal of time and money; you can avoid this by taking care of this now.
 
The opportunity to take care of this voluntary is quickly coming to an end. We would hate for you to lose the option of resolving this before it goes to the next step which is a Lawsuit against you, but to do so you must take immediate action.
 
It is quick and easy: Grab your debit card and call us or e-mail us right now in order to make a payment and freeze down this case. Contact us on 1-585.204.6000