Is the bank account statement yours? Is the account yours? Have your given your father your pin number to be able to access your account?
If the answer is Yes to all these questions and you know your father is a compulsive gambler, then I can only suggest that you change your pin number immediately, keep it secret and never allow him access to your account again. Gamblers, drug and alcohol addicts sadly all lie through their teeth to get the money they need to feed their addiction, and giving them any money at all only served to feed their addiction.
Bank statements are usually 100% accurate. I can't imagine any bank where it would be a regular occurrence for cash withdrawals from a cash machine not to show up on statements, and for the machines not to issue the money either. Time for you to have a serious talk with your father about getting some help for his addiction.