I have really flat feet and was told because of it my calves muscles are over working themselves to compensate for my flat feet. is that true?

It can be.: Do you have any pain? Flatfeet can cause all sorts of biomechanical imbalances. Try using arch supports if you are experiencing any problems.

Yes, Sort of: Because you have flat feet, there is more torque placed on the achilles tendon causing soreness of the calf and possible achilles tendinitis. In addition, another muscle called the posterior tibial tendon may become injured. It is the main tendon that prevents collapse of your arch. Best treatment is to get orthotics to support your arch and stretching exercises for a tight achilles tendon.

Up to a point, yes.: Feet that flatten out too much tend to be unstable. In a manner of speaking, you have less "leverage" when walking, so the muscles, tendons and ligaments have to work a bit harder to do the same amount of work. This makes for a little extra fatigue resulting in aches, pains and possible deformities over time.