I entered a 4-digit passcode but phone wants 6
I got a new iphone 6s Plus yesterday (I had an iPhone 6 Plus) and the guy at Sprint was "helping" me set it up, and said to enter my passcode, so I did. But it's my old 4-digit passcode. I did not click on "4-digit passcode" during setup (now I know I should have) and now I can't unlock my phone because it wants a 6-digit code that I never entered. I have searched and can't find anyone else who had this issue. I tried repeating the last digit as the fourth and fifth digit but it didn't work. I tired my four digits plus 00, that didn't work. I don't want to have to erase data and set up everything again. I spent hours setting everything up.
iPhone 6s Plus, iOS 9.2.1