Amazon.co.uk Exploit phishing page (1701) - suspected to be local

No, I did not. I use Firefox as my main browser, and it was the browser I first encountered the problem with. I did not update Firefox either.

This is definitely a local issue - tested on other computers on the networks I use. Anytime I try to access Amazon on this machine, half of a login (not the usual Amazon homepage) screen loads, then I get hit with this: Screenshot - d8ac111a3c5f499cb6c94483ab6bccb7 - Gyazo
It's only a few days old, but Malwarebytes, AVG and CCleaner haven't fixed the problem. I'm not entirely sure how the networking side of this would work, but I suspect it's hijacking the request to Amazon and sending back a different site masked as Amazon.
Any suggestions?

Do you mean that you receive this same error when you try to log into Amazon website on all web browsers?

Thank you for the clarification Joshua. I think it is a bug. I will escalate this to our technical team. They will communicate and assist you further regarding this. Thank you for letting us know about this.

Hello Joshua. We received the same issue from another customer. He mentioned that he received this popup from AVG when he is trying to login to Amazon website from Google Chrome browser alone. Are you dealing with this same issue? Did you update chrome recently?

No, I did not. I use Firefox as my main browser, and it was the browser I first encountered the problem with. I did not update Firefox either.