Did you afma your lens on this 7D body. This will help a lot for AF. However the 5D3 has a much better AF system compared to the 7D. My keepers rate due to AF is much higher on the 5D3 then on the 7D, even after I have both afma my 70-200.
I also see regular noise on dark and light colour, even on low iso on the 7D. This is not the case on the 5D3. However, that noise is easily to remove even by lightroom. So that's not a big problem. Max noise level I use on the 7D is 1600, on the 5D3 is 6400. And even then I have the impression that the 5D3 is easier to clean-up the noise in Post Processing. So there is a difference of at least 2 stops on noise for the 7D compared to the 5D3.
For those reasons, I rarely use my 7D anymore. The only main advantage between the 7D and the 5D3 is the higher fps (8 to 6fps for the 5D3). While I mostly do sport and wildlife, that's the reason I recently bought the 1Dx.
I don't know how big your problems are with your 7D, but noise in smooth colours and AF compared to the 5D3 can't be solved by canon, cause this is dependant on the 7D itself. How ever, please do post an example with exif info to see if your remarks are really caused by the 7D.