Cannot get Child Theme style.css to override Parent style.css

I’m using a Child theme set up correctly. But I just cannot get changes in the Child theme style.css to be reflected in the site. Tried emptying the browser cache a million times and it doesn’t work!

I’v created child template files and they overide the parent ones fine.

I have noticed in view sourse it puts a version number on the end of the style sheet like this:- style.css?ver=3.9.1 even though I have created no version(or is it just the WP version?).

In another site I created there is no versioning of the style sheet, so why is it being put in automatically when I don’t want it set.

How can I force it to use the most up to date version of the Child style.css file and not version it?

Here’s my site url:- http://www.peterswebservices.co.uk/