£15 off £25 for AmEx card holders when you use any amount of points to pay for total. I used 0.20p and it worked, expires at the end of the month, the code is AMEX16SWP

Use American Express Membership Rewards points at Amazon.co.uk
Shop with Points is a fast and convenient way to use American Express Membership Rewards points for purchases at Amazon.co.uk.

Special offer: Shop with Points and get £15 off your eligible purchase at Amazon.co.uk
Use your Membership Rewards eligible American Express Card to Shop with Points at Amazon.co.uk and get £15 off an order of £25 or more with promo code AMEX16SWP by 31/01/2017.

To receive your promotional discount, you must:
1. Add £25 or more of eligible items sold and shipped by Amazon.co.uk to your shopping cart.
2. Enter the promo code AMEX16SWP in the box provided on the checkout page and pay for at least a portion of your order with Membership Rewards points.
3. £15 of savings will be reflected on the final order checkout page.

Promotion terms and conditions
1. This is a limited time offer. The promotion will end at 23:59 GMT on 31/01/2017 or when 33,333 customers have claimed the promotion code, whichever is earlier. The promotion code will expire concurrently.
2. To redeem the offer, you must be logged into an Amazon.co.uk account which has been active before December 20th, 2016.
3. Offer applies only to the purchase of at least £25 of eligible items at Amazon.co.uk, where Membership Rewards points are used for at least a portion of the purchase and the promotion code is entered at checkout. Taxes, gift-wrap and shipping and handling charges do not apply when determining minimum purchase amount.
4. The maximum benefit you may receive from this offer is £15 per eligible Amazon account.
5. Offer does not apply to the purchase of digital content.
6. Offer only applies to eligible items sold by Amazon.co.uk.
7. Items must be purchased in a single order and shipped at the same speed to a single address.
8. Shipping charges may apply to discounted promotional items.
9. Limit one promotion code per Membership Rewards eligible card.
10. Offer may not be combined with other offers.
11. Offer is available by invitation only, is non-transferable, is not redeemable for cash, and may not be resold.
12. Amazon.co.uk reserves the right to modify this offer at any time.
13. Offer discount will be allocated proportionally among all promotional items in your order.
14. If you violate any of these terms, the offer will be invalid. If any of the items related to this offer are returned, your refund will equal the amount you paid for the item, subject to applicable refund policies.
15. Promotional codes (including those placed directly in accounts) may not be redeemed for Amazon Gift Cards.
16. This promotion is available only to Amazon.co.uk customers with an eligible American Express card issued in the United Kingdom.