Hi
I think if you did the treatments right, you did your best. The problem with lat. epicondylitis is that it is no -itis, no inflammation. It is a degenerative overuse process caused by repetetive micro trauma. in early stage it can be treated with several techniques but in later stage (chronic) surgery is indicated most of the time to reduce the tension on the common extensor muscles tendon.
dont want to rob your illusions, but in chronic stage its gonna be a hard way to treat conservatively.
cheers