Date and time have to be constantly reset.

Date and time have to be constantly reset.

My camera will not hold the time and date after the camera is turned off. Every time I turn the camera on I have to reenter the date and time. I know that there is an internal battery but do not know how to access it for replacement or recharge if it is dead. It seems as if this if the problem. Canon's website is of no help and after several unanswered emails I have given up on them. Can anyone help?