i have alarms on my windows..?
my 3yr old son actually pulled one of the kitchen cabinet doors off one day when he couldn't get into it. I know exactly what you are going through. All I can tell you is try to set limits, and stay strong on your word. Take away a favorite item for bad behavior. And take the locks off. my son was not as interested in getting into stuff after a while when i just took the locks off.
Replace the pipe with a new one. Nothing is better than doing the job right.