I bought an item on amazon through a marketplace seller. Have done this before (though not this seller) with no problems. Item was under £10 and was a business rather than small private seller. Reviews fine 
Said 3-5 days delivery. Item was apparently dispatched day after I ordered. I say 'apparently' because it claimed it was dispatched to royal mail on a sunday, when as far as I am aware royal mail do not collect, even as couriers on a sunday. The item took 13 days to arrive. I emailed seller after 11 to ask where item was. I did not get a reply. Eventually item arrived. I got email from amazon to rate seller. Funnily enough I gave a bad review, saying item was fine when arrived but took nearly 2 weeks and seller did not respond to email.
So I've had a phonecall (my mobile number is on the amazon account) from the seller saying they responded to my email and have something to prove it was received (the only thing I know that does this is a read receipt and considering I didn't receive it let alone read it I don't know how they can have 'proof'). Asking me whether I was looking for compensation
and wanting me to remove/edit the review. They put a hell of a lot of pressure on me, essentially saying I was lying until I deleted the review to make them go away. I have had missed calls from this number but didn't recognise it so didn't try to call back.
This type of pressure doesn't usually work on me and I don't usually give a crap but this really upset me at the time and now I'm just really angry at them. And amazon for giving them my phone number tbh. I have emailed amazon with a complaint but not naming the company as I don't want to receive further phone calls from them. I don't know if they'll be able to work it out anyway.
I will say though if you have an amazon account I would not have your phone number on it if you are buying from marketplace sellers. I have removed mine now. Waiting to see what amazon says but really cross with this. Makes the reviewing system pointless if sellers will just harass you to remove bad reviews.