We have a 200 amp meter head box mounted on a telephone pole approximately 150 ft. from the house. The wire comes in from the transformer to the telephone pole down to the meter head box out and back up to top of pole. All is connected together with one wire going to barn to 200 amp box and the other wire going to the house to a 200 amp box. My question is.. we just built a garage 20 feet from house How do I get 200 amp service to the garage?

I can tell you this much you cannot keep attaching 200 amp boxes to a single 200 amp service. I would tap out of the house panel and run a circuit to the garage.