On this page:

https://www.mazda.co.uk/buying-owning/maintaining/dsr/

It says

if your copy of your Digital Service Record gets damaged or lost you can ask your dealer for a new copy.

Phone call to the local Mazda dealer where it resided last would be my first call, or any competent Mazda dealership.

If no joy there try customer service at Mazda UK, if anything like Toyota they will know from 'puter where and when it was serviced even if they don't have details of work done, or didn't at the time due to system upgrades.

Don't be surprised if you get odd reactions upon enquiring though, when i enquired about some specific recall work on my current Landcruiser i had to phone several Toyota dealers across the country, most were helpfulas one would expect but one lady on service reception must have thought i was some sort of Bond villain trying to access military secret data from her attempt at trick questioning.

Unfortunately its a better system in many ways for you as a buyer, its possible (or was) to buy stamped up to order service books on certain sites, it would take some serious jiggery pokery to enter a false SH on the dealer's computer system.

Agreed, I know someone years ago who bought a used Nissan SX with just the first 2 years services stamped up in the book and his local Nissan dealer stamped and filled in the missing 6 years for a small fee. Hopefully the electronic system will stop this.