Just an update. Good news, I have phoned Amazon and they almost immediately offered to send a courier and issue a refund. After reading up on my rights according to SOGA they had to I suppose. Credit where its due though – thanks Amazon.
Thanks so much for all of your input too. I owe you a pint!
Send a 14 day notice. Proceed to small claims. I did this with a faulty telly from online company. Must be fit for purpose etc. Got money back and bought next one from John Lewis. Didn’t need to actually do small claims part. Also handy having a sister who is a lawyer.