Suffolk County National Bank counterfeit bills Southampton, New York

On Friday Nov 30th, 2012 I went for a dr's appt.  My copay is $50.  I used a $100 bill from the paycheck my Husband cashed at Suffolk County National Bank in Southampton NY.  As he does every Tuesday. That is where his boss banks.  We don't.  I get home from my dr's appt and I receive a call from their accts dept. telling me my bill was suspect and that the federal reserve has been informed and it will take 2 weeks for an investigation to be completed.  I called the bank immediately to let them know of the situation, to which they replied.."It's NOT their problem.  How is it that you can walk into a dr's office, pharmacy and a supermarket and they check you 100's but a financial institution doesn't?  Despite the fact that I am out 100, I guess it could be worse.  It could have been all the other bills that have been suspect, but weren't.  When I called the bank again to try and speak to a branch manager, surprisingly there was no one avail.  I was asked if i had a receipt.  Clearly this person at the bank has not been working there long.  If so, she would have known that you aren't given receipts for cashing checks.  Only for withdrawals and or deposits.  She also told me she would have someone contact me.  And to no avail, no phone call has yet been returned.  Where I live is in the Hampton's.  Those that know the area know it is a very small area.  Incidents such as this are pretty easy to seem suspect and is easier to track than say a larger city, yet NO one has yet to talk about this.  Several small business with in a 10 mile radius, maybe more, have recently put up signs, including the gas station next door to me saying they are no longer accepting 100 bills due to the increasing distribution of counterfeit 100 bills.  I have to also mention that a couple of months ago a co-worker of my husbands cashed his check, same bank, and a a few minutes later went to go pick up his prescriptions from our local pharmacy and handed the cashier a 100 from again the "same bank", and with in minutes were met by law enforcement.  Luckily he had been left alone.  What I don't understand is the bank gives us the counterfeit bill and we go and use it and WE get arrested.  Yet the bank who "Is Not Responsible" does not suffer any consequences for not doing their job?  This REEKS!  Even the acct person at my dr's office who happens to have the same bank different branch got the same answer " Its not their problem" is befuddled by this as well.  I have contacted our local networks and waiting on someone to help with this epidemic of counterfeit floating around the Hampton's.  I even called the FBI however they seemed un interested and told me if there was any legal action against me to call them back and they will give me the # for the secret service?  What?  I felt like they had a laugh and just brushed me off.  Not funny if you are a law biding citizen and you get in trouble but again a financial institution doesn't.  Frustrating, You just cant trust banks!  You can't trust credit card companies and now you can't trust CASH!  Some one please help in preventing this from happening to another innocent law biding citizen!