Hello Bob,
It is a matter of law, and the relevant law is the Sale Of Goods Act (SoGA). This applies to all new retail products, and is commonly know as the warranty. The warranty is automatically part of your statutory rights, and it forms part of your contract to purchase from your seller. It is different and not connected to the manufacturers guarantee.
It may be worth noting that if you have used a finance deal to HP the caravan, then you are technically buying from the finance house not the dealer. Under these circumstances it is the finance house who is responsible for the SoGA warranty.
The Consumer Association's magazine Which? Provided a free booklet "How to complain about goods and services" (1993 MG41 page 5).
(Start quote) "A typical example: you buy a pair of shoes in a sale. A week later a strap comes right away making the shoes unwearable. What should you do? It is best to take them back as soon as you discover the defect. If it is impracticable for you to return to the shop at once, perhaps because you live a long way off, or because the goods are bulky, write to say that you are dissatisfied with the product and ask for collection arrangements to be made. Any unexplained or unreasonable delay will weaken your case. Many people believe that the initial complaint about faulty goods should be made to the manufacturer. This is not the case. Your contract is with the retailer who sold you the goods, and so it is to the retailer that your complaint should be made." (End quote)
The essence of the SoGA laws is that as a purchaser you should be no worse off because of a fault or failure if the fault had not occurred, so for SoGA warranty claims you can claim only reasonable expenses.
SoGA only applies to faults that were present at the time of sale. It would also apply to failures that can be attributed to a fault that was present at the time of sale. Claims under SoGA are not time limited, but the Act does consider the life expectancy of a product as it would be unreasonable to expect to claim against a bunch of bananas more than a few days after purchase.
The burden of proof that a fault exists changes with time. For a caravan any manufacturing fault discovered in the first six months, it would be for the seller to disprove it was a SoGA fault. Beyond that it is up to the buyer to prove it is a SoGA fault. As a product gets older, any liability will also diminish. In practice it would be almost impossible to bring a SoGA case where a product is more than 6 years old.
Other failures that fall under the Manufactures Guarantee do not attract the same level of consumer protection. The manufactures are not legally obliged to offer a guarantee, and when they do, they can be highly limited. It is essential to read the terms and conditions offered by your manufacture. It is unlikely that the manufactures guarantee covers your costs of delivery and collection from the approved repair shop, though depending on the individual circumstances and the nature of the fault and level of inconvenience or costs incurred. Some manufactures may make a 'good will' offer to cover some or all the costs.