Asterisk IVR for account balance

I need an IVR that when the person call in to my box they would be prompt to enter an ID number from 5 to 12 digits after entering and presing the # key a DB lookup is performed to retrieve and play the ID owner account balance after that I would like to have an option to to disable it or enable it using the "true" "false" to in case I want to use it to play at the end of the "if you want to pay this outstanding balance press a digit or stay on the line and you would be conected to a agent" and the perform a exten => Goto....