Seems good to me 5% extra.
Account specific - GOOD LUCK
Terms and Conditions of the Promotion
Get an extra £5 added to your Gift Card Balance when you Top Up £100 or more in a single order on Amazon.co.uk ("Offer"). In order to qualify for the Offer, you must: (1) have received an invitation directly on Amazon.co.uk; (2) click the button 'Click to register for the Top Up reward’; and (3) Top Up at least £100 in a single order on Amazon.co.uk.
For qualifying orders, an additional £5 will be automatically applied to the Gift Card Balance of the Amazon.co.uk account used for Top Up, after the qualifying Top Up order has been processed. In the case of Auto Top Up, the reward will be applied after the order is processed and delivered to your Gift Card Balance. An email notification will be sent to you to confirm the application of your £5 Amazon.co.uk Gift Card reward.