Product: Money transfer, virtual currency, or money service

I was selling an item on XXXX and was reached out by someone for the item that she was willing to pay an extra {$70.00} for. So the initial agreement amount was {$590.00} that would be sent to me via cashier 's check. I have very little knowledge of checks but the one thing I assumed was you can not put money onto a cashier 's check without actually having the funds nor can you take back that money once its been deposited. I did my research on this. Once I received the check which was a Bank of America check, it was made for total {$2900.00}. Of course this was extremely alarming so I reached out to the woman and asked if there was some kind of mistake and she had said no, the extra money was meant for the shipper/mover that was going to come get the item I was selling to her. So I had assumed I was going to hand them cash after withdrawing the money, so I deposited the check via my phone on the banking app on XX/XX/19. I waited for the money to show it was no longer processing on my account which took over 24 hours and had shown a formal deposit on my account on XX/XX/19. So then I informed the buyer it was officially deposited and was directed to send shipper money to someone through both XXXX and XXXX. Again, a red flag but I had assumed that since the money was in my bank account and that XXXX was backed by my own bank ( Bank of America ), that nothing could go wrong. If anything did, I would be helped. So far I've filed a police report and contacted my bank numerous times but my bank does not seem not even willing to help despite this being the first time this has ever happened to me in the 2 years I've been with them. I'm now in the negatives and as a XXXX year old there is no way I just have that much money to help at least keep me above zero. Now I find out that XXXX has no fraud protection that is backed by my bank. A money transfer service I only trusted because it was backed by my bank. I sent {$2000.00} through XXXX that morning on XX/XX/19. Later that night I got a notification that my account was overdrawn and there was a debit hold on the check. The first BOA representative explained that the initial hold on the check AFTER I had sent the money was for them to verify the funds with the other bank, she mentioned nothing regarding that it was a check with a stopped payment. I had asked that if the check did not go through would my XXXX payments go through and I was reassured they wouldn't. But that was a lie, since now I'm overdrawn. Why was the money made available for me to even touch if it wasn't actually validated yet? And why did the representative tell me the money would not go through when it clearly did and then every BOA representative after her, even the manager at a store had said there's nothing they can do to help. Even the store manager had looked at the check and saw it looked extremely real, and despite using her UV light to show me the watermarks they were barely visible. Not even their fraud department is picking up after an hour on hold. I'm scared and terrified, and it seems that I as the victim of scam am not even able to get any help from my own bank.