You should always communicate in writing. It is too easy to be ignored if you are telephoning. Your letters will create a paper record that you can refer to, especially if you send the letters by regular AND certified mail, receipt requested.
There are mortgages that are held in a "bundle" with other mortgages, and the bundle is owned by a group of investors. Often, but not always, no changes or agreements can be made about the mortgage without investors' approval.
You might also want to ask [in writing, of course] if the bank will accept a deed-in-lieu of foreclosure. The bank is not required to agree to this.
Your county court may have a special program to deal with foreclosures and you may be able to go through that process to get a response from the mortgage holder.
You may require the services of a lawyer to resolve this.
This response is not legal advice, since I do not have all of the information that would be required, and I do not have a representation agreement with you.
* If the answers to your question confirm that you have a valid issue or worthwhile claim, your next step should almost always be to establish a dialog with a lawyer who can provide specific advice to you. Contact a lawyer in your county or township.
* Another reason for contacting a lawyer is that it is often impossible to give a good answer in the Internet Q&A format without having more information. The unique circumstances of your situation and things that you may not have thought to mention in your question may completely change the answer. If you want to be sure that you have a complete answer to your question and an understanding of what that answer means, establish a connection with a lawyer who practices in the area of your concern.