Very poor service & poor quality grey imports.

I bought a Sigma 17-70mm lens which arrived with a severe focussing fault - the lens would not focus correctly, the motor whirred and tried to focus but under many different light conditions it would not focus correcltly.
It took two weeks before I was in possession of a replacement lens which was also faulty. I used it on a job (I have been a professional photographer for nearly 30 years) and it was very noticeably soft on the left (but not right) edge of all images when at wide to medium focal length. I carried out a lens test when I realised the fault but ProCamera Shop said it was 'within tolerances'.
I contacted Sigma UK who informed me that they would not personally examine the lens because,according to their records at hand, Pro Camera Shop were not an approved importer and that they, Sigma UK, would not guarantee the lens that I had bought.
I have just received a full refund from Pro Camera Shop but this whole process has taken well over 4 weeks.