I have found that I sometimes need to change practitioners to find one who works with my body and ailment better. I have seen this with PT's and chiros.

There is a self therapy that helps with these issues. You connect a rubber stretch therapy band to a location at shoulder height. Then, you pull on it and pinch your shoulder blades together. This strengthens the muscle and helps to correct the poor positions of vertebra and other upper back and shoulder anatomy.

It does not seem like much but it works great.