Invasive surgery I'd consider a gamble. If you are fully aware of how the problem manifested, then there is a source for the solution. If not, then surgery is literally a stab in the dark.
How long do you hold the stretch for?
The blood supply for a tendon is comparatively poor, so for it to get the messages to lengthen permanently, you'll have to put it under mild tension for at least 10 minutes.
Re alignment of muscle fibre only needs about 2 minutes.
Sorry if you've already done all this before.