Royal mail Prime Tracked 24 service delivery with signature Concern

We are doing Amazon Seller fulfilled Prime orders through Mintsoft with Royal Mail service. We have Prime Tracked 24 service linked to our account, but we need the same service with signature for orders above a certain value. Adding a signature to these orders will provide additional safety and help resolve delivery issues where customers claim items were not delivered despite having photo proof of delivery. We are requesting here as an additional courier service with "Prime tracked 24 & Signature" addon to Mintsoft?

Finding a solution for this would greatly improve our delivery process and customer satisfaction.

Thanks and looking for positive responses from your team