Upload & Sell: Off
My advice would be to stop right now and send for calibration your camera and lense (note the singular because I'm not sure your Canon center would calibrate a Tamron lens). Don't waste your time and money anymore.
I had a similar problem with f/1.4 or f/2 lenses and the same bodies (2 7D). I spent hours, bought many things that would solve the issue (and spending more hours to have them working properly - e.g Focal "PITA" software). I was confident of my "counter measures" until being in the fields with random results.
Finally, I stopped everything and for months, when I needed an accurate focus, I relied on CDAF and LiveView (and tripod, and so on). But that was ok (I do mostly landscape and still lifes) and results were excellents.
Now, I'm using a 1Dx and all my lenses are working fine with PDAF (some requiring a small MA).
To conclude, if a small adjustment (I would say between about -10 and +10) doesn't work for every focal and every distance, don't go further. Especially with not so luminous lens (you should not have such an issue with f/2.8 lenses).
If you could (and want), I would suggest to start with the calibration of your 7D alone, insisting that your Canon center checks the flange focal length and the flatness of the sensor (I hope my translation from French are right). Next, if required, ask for the calibration of your lenses (without the body).
The purpose of this two-step action is to not "bind" your lense to the camera. Thus, changing the camera would not affect your lens anymore (well, honestly it would reduce the risk with a new camera because it depends on how well this latter is calibrated !)
I hope it's clear, and sorry for my English (not my native language).
Edit: fix the biggest errors, well at least from my knowledge :')