Think about Insurance agents, They are not held liable if an insurance policy claim is declined or the insurance company goes bust - It the same process.I’m still not comfortable with the Agents role described.
Manufacturers' agents or representatives are independent contractors who work on commission to sell products for more one or more manufacturers.
Some sell Bailey and Swift etc. I can see nothing in CRA that says an “Agent” can sell things and be exempt , even a warranty.
It is further noteworthy that the Warranties I have seen specifically tell you to consult your Dealer not the Manufacturer.
With regards how you make a claim, that is down to how the particular manufacturer or policy owner decided they want you to make contact.
In the case of the caravan warranties they prefer to take claims via the dealer, but the liability only rests with the manufacture.
May I suggest you try to get your dealer to accept the liability for any part of the manufacturers warranty if the manufacture delines a claim.