oneeyeluke said:No No No, don't prune your thuja because you said they have stopped growing. If you prune a tree that has stopped growing you will kill it. They must be in super health before pruning is done in the Spring. Thuja have massive heights between 20 to 40 feet tall. They also spread out and grow to be about 12 to 20 feet wide. So be patient.
The contractor planted the two plants too deep in the soil. Take a hand cultivator and loosen the soil around all the plants. Everytime it rains loosen the soil and keep it lose all summer and by next Spring they will be healthy enough to get a pruning.