Product: Checking or savings account

On XX/XX/XXXX I wrote a check ( # XXXX ) in the amount of {$1900.00} to XXXX XXXX from my business checking account and dropped it in the mailbox located at the XXXX XXXX on XXXX XXXX XXXX XXXX, NY. On XX/XX/XXXX I discovered that the aforementioned check cleared and the payee and amount had been altered. The payee was changed to XXXX XXXX XXXX and the new amount was {$7900.00} ( they changed my " XXXX '' to a " XXXX '' the number and the word one ). The white out they used was grossly evident ( especially on the word nine, the addition of the " XXXX they squeezed in as well the lines at the top of the boxes under the word have a few spots missing from the white out ). 
On XX/XX/XXXX I went to my local Chase branch to report the fraudulent activity that took place on my account and spoke with a Customer Service Rep by the name of XXXX. XXXX contacted the Chase Customer Claims Department, we explained to them the details of what took place. Chase Customer Claims Department told us both that they would mail me a declaration to sign and return and that I would be reimbursed within 90 days. I received the declaration in the mail, I completed and signed the document and sent it back Priority Mail on XX/XX/XXXX. Upon tracking the package, it was confirmed that Chase received on XX/XX/XXXX. On XX/XX/XXXX I called Chase to inquire about the status of my claim and I spoke with a gentleman by the name of XXXX. XXXX XXXX asked me for the tracking number. After giving him the number he said that they would send me a letter regarding the matter. A letter was never received. On XX/XX/XXXX I called again to inquire about the status and spoke with someone by the name of XXXX. XXXX XXXX stated that he did not understand why it was taking so long to process my case. He also confirmed at that time that my declaration that was required of me was received on XX/XX/XXXX, but they did not open the file for final approval. He stated that they would follow up about final release within the next 30 days. On XX/XX/XXXX I visited my local branch and spoke again with XXXX to voice my concerns about the banks failure to resolve the matter and reimburse my account within the 90 days as promised. She contact the Loss Claims office in XXXX XXXX, Tx and spoke with someone by name of XXXX who confusingly stated that my package was never received. I read her my record of contact with their office to include informing her that on XX/XX/XXXX I spoke with XXXX who confirmed receipt of said package. She then requested that I sign a new declaration and give it to XXXX ( which I did ). She stated that by doing this again it would speed the process up to be resolved within a few days. On XX/XX/XXXX I revisited my local branch to inquire of the delay and spoke with XXXX who seemed to understand my concerns. XXXX contacted the Loss Claims again and they stated they were waiting for the new declaration that XXXX insisted that I signed ( that would speed up the process to a few days, which proved to be false ). At that point I had to convince XXXX that the original package was sent and received on XX/XX/XXXX and was confirmed received by XXXX. XXXX then challenge their statement in saying they never received it. They then told XXXX that they did receive it and that they were waiting on XXXXk XXXX XXXX ( who cashed the check ) to reimburse Chase before they would compensate me. I asked what happens if XXXX XXXXXXXX XXXX doesn't reimburse them? XXXX said Chase would then reimburse me. Since that meeting I have received a letter from Chase appearing to shift blame to XXXX XXXXXXXX XXXX stating that they are awaiting on the claim with them to be resolve before I am reimbursed. 
To date I have yet to be reimbursed nor have I heard from Chase concerning this matter therefore I am filing this complaint because it appears that Chase has been giving me the run around from the beginning and they don't appear to be any closer to resolving this matter. This loss has been detrimental to my business especially in light of covid and having already being affected by loss in rent ( due to tenants failure to pay ). I am hopeful that you can help bring a swift resolve to the matter as Chase has been very neglectful from the start to with accepting said check. I have had this business account with Chase for about 33 years therefore it would seem that the fact that I never write checks this high in my 33 years history would raise a red flag which in-turn should cause them to do their due diligence by contacting me to confirm that the check was not fraudulent. I don't know who the worse scammers are between the person who took and altered my check or Chase.