My parents did the same thing to me. They did eventually buy me the bike I had been saving up for, but as a birthday present, so I am not sure if it really counts as repaying me. I forget about it for the most part, but when I remember, I am still angry.

What your mother did sounds pretty bad. Why not bring it up the next time you have both of your parents on the phone at the same time? Maybe your father would be interested in knowing now. That's awful, to steal a little kid's money and then tell them not to tell anyone.