Product: Mortgage

My loan servicer was switched from XXXX XXXX  XXXX to Freedom Mortgage in XXXX of XXXX. I received and paid bills to Freedom Mortgage every month XXXX, XXXX, XXXX, and XXXX. My XXXX statement showed me up to date and I made my regular payment on XX/XX/XXXX. I received a letter telling me that my account was past due on XX/XX/XXXX. To the best of my knowledge, on XXXX XXXX, {$2000.00} was debited from my account. The explanation was originally it was sent back to my prior loan servicer XXXX XXXX  XXXX. They told me to contact XXXX XXXX  XXXX to find out what happened. XXXX XXXX  XXXX said that the loan switched and since then there has been no activity on my account. Also, they stated that there has never been a transaction of {$2000.00} in my entire account history. My payments for my mortgage are {$1700.00}. 
When told this Freedom Mortgage said I had a payment returned to my financial institution. They cant provide this documentation and I have since sent them statements that show no such payment was returned. It has been almost 2 months since this began. I have begun doing all transactions on email since I want a paper trail and also, I have spent too many hours on the phone trying to resolve this. I have included all the phone conversation notes below. This includes details of their responses. 
On XX/XX/XXXX I received a letter dated XX/XX/XXXX stating that " your loan is now two payments overdue. The total amount due to bring my account current is {$3500.00}. This information may have been reported to the credit bureaus. '' I called on XX/XX/XXXX at XXXX XXXX  and spoke to teller # XXXX XXXX. She said she couldn't figure out the problem on my account and forwarded me to to XXXX # XXXX in the escalation team. After 42 minutes speaking to XXXX, they said they needed to call me back and that the department that needs to investigate this is closed. They assured me that I would hear back the next day in regular business hours. On XX/XX/XXXX at XXXX I called back and spoke to XXXX XXXX She could see that there were notes in my file that late fees would be frozen but that XXXX was on the phone and still hadn't heard back with the information needed. ( 22 minutes on phone ) On XX/XX/XXXX, I spoke with XXXX # XXXX in the management team for almost an hour. She sent me a direct email because she said I should have heard back. She said there were no notes to explain what had happened and that was unacceptable. She emailed me and the cash department and said to email her back or that she would email me information She said I should have to keep calling and waiting and getting the same response. She said it would probably take about a week. 
On XX/XX/XXXX, I emailed XXXX and never got a response. 
On XX/XX/XXXX, I called her and left a voicemail, no response. 
On XX/XX/XXXX, I received a call in attempt to collect on defaulted mortgage. I was very upset and asked to speak to the escalation team. The agent said she was sorry she could see notes in the system but couldn't figure it out. She sent me to another agent. I spoke to XXXX # XXXX. She said they had no updates. She assured me that the will email the cash department again and to call back on XX/XX/XXXX. She again personally emailed me. She said that it appeared that they had sent my payment back to my bank account. She asked me to send a copy of my bank statements for XXXX to show that I never received the payment. I emailed her my bank statements that day. She said she would follow up. Again no response. She is not replying to emails. 
At this point, I began emailing through their website. The responses have never answered my questions. One response was not even in regards to my question and seemed as though they sent an automated response regarding escrow information. I seem to be getting no where and dont know how to get a resolution. 
I feel attacked, I cant stand receiving emails and phone calls and letters saying I am in default when I havent missed a payment. I feel harassed  and they cant answer my questions.