Anyone else with trouble contacting a company try the CEOEmail website. Google CEO Email and the name of the company and find their listing in the search results. It's an excellent site for complaining as they try to collate the actual email addresses of the heads of most big companies. But...
Enjoy the sun sir, beautiful day here in Hangleton.
For when you return...
Email cs-reply@amazon.co.uk
Telephone 0800 4961081 (Direct)
Switchboard 0207 084 7911
Website https://www.amazon.co.uk
Postal Address 1 Principal Place, Worship Street, London, EC2A 2FAM
Oh... The old 'I was just testing my eyesight when I filled in the form' excuse.
Seriously though, I recall there used to be some legislation about 'unsolicited gifts' that runs along the lines of... If you make all reasonable attempts to get them to take it back and/or stop, then you are...
If it's small... Post it back in a post box.
Amazon will soon take action when they are paying 'normal' return mail fees rather than what they agree with their own couriers.
If that doesn't get their attention, write them a letter (with no stamp) and keep doing it until they actually take action.