I'm not trying to excuse Stena's use of 084 numbers but that page is clearly B2B. For clarification:
1: In B2B environments is it permitted to use 084/087 numbers for all purposes, even where it would be forbidden for B2C?
2: Again in B2B is the cost declaration required?
Here is another example. RS Components, who clearly position themselves as B2B only, have an 0845 number on their home page with no declaration:
https://uk.rs-online.com/web/and elsewhere, inculding this customer support page:
https://uk.rs-online.com/web/generalDisplay.html?id=support/cant-be-returned