Hi Panayiotis,
We're glad to look into this & help you.
Please let us know whether the site is inaccessible in Firefox alone or irrespective of browsers.
Also, let us know the version of AVG that is installed on your computer (Open AVG - Menu - About).
AVG Internet security is all of a sudden blocking access to amazon.co.uk
AVG Version is 21.5.3185 (build 21.5.6354.680)
And it is blocked on all browsers. I've had to add it to the allowed/exceptions list in order to access it.