Hello Graham,
Well done on spotting this fact. How many of us don't bother to check that the tyres are correctly rated after having new ones fitted?
Based on the information in the previous posts you have supplied, In my opinion I have no doubt that the service centre is clearly at fault.
They had a clear instruction from you. (I assume you did not instruct them to fit a particular make or lower specification) and they have supplied goods that are definitely not fit for purpose by fitting tyres of lesser specification that the caravan manufactures design.
As a business trading as a caravan service centre they should have adequate expertise about the specification and fitting of spare or replacement parts for caravans. It is not unreasonable for you to rely on their 'expertise' to carry out the job to the correct specification.
The supply and fitting of inadequate tyres is in my opinion is fundamental negligence on their part, especially as they had 'pattern' to follow, and 'working' knowledge of caravans.
The service centre should be bending over backwards to help resolve this failure on their part. I would venture to suggest that they should be prepared to replace the tyres at no extra cost to you.
I must point out though, If you took these inadequate tyres on the road, the caravan would be classed as un-roadworthy. As the driver of the vehicle you are solely responsible for the vehicles condition and compliance with the statutory regulations. I hope and assume no incident occurred whilst on the road but during this journey your insurance would have most likely be invalid.