Product: Checking or savings account

I deposited a check for a friend that asked me to because he needed to pay his mortgage the following day. I verified everything was legit with him and proceeded to deposit check on my account via atm. I then waited for check to clear the following day ( XX/XX/XXXX ) and then went into the XXXX location in XXXX Oregon and withdrew {$1100.00} of the {$1800.00} so he could make his payment immediately and was going to withdraw the reminder later that day. The following day I checked my account balance due to a attempt to pay my electricity bill didn't go through due to non sufficient funds? It said I was over {$600.00} negative and the bank had taken all of my money from savings and checking which totaled more then {$1200.00}! I called immediately And the bank teller told me rest assured this would be squared away I just had to sign the back of the check come to find out I forgot to sign the back of the check my deposited it she said it has been sent out to me I can sign it and come into the branch with it and it would all be cleared up. I said okay. Then the following day i received a letter ( that quick?? ) Stating the check came back fraudulent and they were taking all of my money AND I needed to make payment to bring my negative balance current, immediately! I've been fighting with them ever since.. been hung up on, passed around, to then be disconnected AGAIN! Day in & day out, I've been passed to the next customer service agent and the next, and been told there is no protection for me, I lose, and that's that! Well I opened my account being told I'm protected from fraud with atm, checking, savings & debit transactions. Now I suddenly have to foot the {$1800.00}? Then I was told to make a police report then bring it in to the branch and they would notify claims dept. And I would be refunded my $ immediately if I'm willing to press charges! I did exactly what they told me to do, brought in my police, report # etc. And they called resolution center and sent me home stating they would take a few days too complete investigation and then get back to me. I was then called on the phone, exactly one hour and 12 min later saying I was denied and that's that! I asked how on earth they investigated that quickly and could do a thorough job, and asked to appeal they're decision please? They told me they do not have a appeal process and do not allow their decisions to be appealled. I was shocked, I called the next day and asked same thing and different rep told me sure, they'll put ne through to their resolutions, team that can help me with that! I was then on hold for one hour and 48 min all to be disconnected after a rep picked up phone than abruptly hung  up! I can not tell you the last time I have been treated so badly and unfairly. I'm absolutely disgusted and I feel they are completely scamming me to not have ru reimburse my money. After researching online I see I am not Alone with similar situations from fellow consumers. I don't understand how and why the check was processed when I failed to sign the back of the check, in error, but at that. Then when I'm a victim of fraud. Made the police report, did what they asked and denied within the time it took me to drive home! Then to be told they're is no option to appeal, but told there was by another rep? Please look into this, as this is not good nor fair business practice and literally stealing money from my accounts wrongfully. I appreciate it