9 weeks post breast reduction and feeling very frustrated. How long does it take for tunnelling wounds to heal?

The "T" junction is notorious for wound breakdown.  The wound healing time varies from person to person. 2-3 months is a good estimate of healing time from the initial wound. Please continue to see your plastic surgeon.  

This is a problem when sutures get infected or you react to the sutures.  It will take time and possible removal of the suture material.  I would see your surgeon as soon as possible.

from such wounds takes time.  And the speed at which it happens depends on several factors.  If you smoke, you must stop.  If you have debris (yellowish tissue) in the depths of the wound, it needs to be removed by your surgeon.  If your wound is very deep, it will take longer to heal.  If you take steroids, it will delay your healing as well.  Everyone heals at their own pace but you must maximize your healing environment to heal as fast as possible.