Is this a scam?

[Duchessofspace]

Just received this in the post - my full name, my real address and postcode and yes I did buy these a couple of months ago from Amazon -but I’ve never been contacted by a company after and certainly not unsolicited by post? Alarm bells are ringing here. Is this normal?

It's a scam in the fact they are fishing for 5*reviews I doubt the gift cards actually exist, and they are banking on the fact that people will leave a review and then forget about the gift cards.
They will be the actual company you purchased from, just stocked and delivered by Amazon

If that company are caught soliciting 5 star reviews in this way, they will be banned from Amazon.

If you are caught being paid for a review, you will get banned from Amazon.

That is why they don't want you to mention that you & they are breaking the T&C on the fake review they want you to write.

It's dodgy & I have no clue if they'd actually give you the £15 voucher.
They might do as they are soliciting a fraudulent review from you.

It may get flagged as suspicious activity on your account getting a voucher after writing a review if you don't normally leave them.

It's not a scam as such but it is a dodgy way of getting reviews.

Report them to Amazon, just forward the letter to Amazon and they’ll do the rest

They’re trying to persuade you to leave a fraudulent review and breach your contract with Amazon.

We need to get sellers like this off Amazon!

I've seen a lot of people on amazon openly say they got something free from the company for leaving a five star review, I don't think it's unusual at all. I've also read some give the free gift and some don't.

I would just scan the letter in and report to Amazon

The vocabulary alone on the letter would get my hackles up!
I wouldn't go anywhere near it OP.