Product: Money transfer, virtual currency, or money service

It started when I tried to sell my car online. I was made an offer on my car and the buyer sent me a cashier 's check ( please see attached for copy ). I went to People 's United Bank on XX/XX/2020, to deposit the check in my checking account at my local branch in XXXX, CT located inside the XXXX XXXX XXXX grocery store. As I deposited the check, I watched the teller put the check in a scanning machine, which I presumed to be the machine which would verify it's genuineness, input data, etc. The teller then told me that the check was " good '' and would be ready to use by the next day. She then corrected herself and said it would be available to be used immediately. I thanked her and then walked away. I then turned around a minute later to ask why the check would clear so quickly as typically when I deposit a check it usually takes 3 business days or so to clear. She explained that because of the type of check it was, it processes and clears faster. 
I then left and immediately checked my bank account to make sure it was actually cleared and available. It showed the transaction as " pending '' so I decided to wait until it went through and was no longer " pending ''. 
The next day on XX/XX/XXXX, when I checked my online account, the transaction no longer said pending so I proceeded to withdraw a portion of the check, {$4300.00}, in cash to buy gift-cards to send the " tow truck company '' to pick up my car. When discussing with my mom the situation at hand, she did a quick XXXX search and soon realized that the check was fraudulent. 
I immediately called the People 's corporate office and asked that they verify if the check was real or fake. I was told within a few minutes that the check was fake and that because I personally withdrew the cash from my account, they would be unable to reimburse me. 
After ending my conversation with them, I tried to reach out to the scammers so that they would return my money, I filed a report with my local police department, and I attempted to call back People 's corporate office on further guidance. They again reiterated to me that they were unable to refund my lost funds. I explained to them that I was told by the teller that it was a good check and that I had no idea that a cashier 's check could be fraudulent. I also explained that I am a naive customer who relied on the expertise of my bank and its employees to detect a check 's genuineness. I was never informed that even though a check may be " available '' in my account it does not mean it is a " good '' check. I was instead met with responses of rejection and blame, such as : " Sorry, even though it's not my fault. ", " It's the responsibility of the customer to only accept checks from people they trust. '' and " Next time, you should inform the teller the details of your car selling transaction so they may better inform you. '' None of these details were mentioned to be before this incident occurred so I did not do any of these things. One representative who was the manager at the corporate office ( XXXX employee # XXXX ) even hung the phone up on my father and I on XX/XX/XXXX at XXXX EST as we tried to plead my case and then lied about it when we called her back. As a customer I was left in the dark about the possibility of a fraudulent cashier 's check, the steps that should be taken when depositing large amounts, and the fact that my bank would not tell me immediately if a check is real or fake ( even though when I called their office after the fact they told me it was fake right away ). For such a large check, {$21000.00}, these details should have been disclosed to me so that I may take appropriate precaution. I have purchased and sold cars online many times before and have never taken these steps or have been told to take these aforementioned steps. I was also told by Corporate office and my local branch that they would leave a message for the Customer Experience Manager explaining the situation so that they may reach out to me for a further resolution, however, I have not yet received that phone call.