Hello Eddie,
I don't condone the time you have been waiting, but quite frequently these thing do take longer than we would like.
Sometimes these matters are controlled by the terms and conditions of guarantee so do check them. Perhaps the dealer is having trouble sourcing the parts for your year of caravan.
However you are the customer and you have certain expectations which are not being met, so what can yuou do?
First and foremost be firm with your dealer write to them and let them know you are not happy with the time they are taking. Do not loose you rag keep it professional. Keep a detailed record of communications such as when, to whom and what was/is said.
If you used a finance package to purchase the caravan (even a credit card for the deposit) let the finance houses know of whats happening, as they may also have responsibility under SoGA.
If you continue to be unhappy, make sure you exhaust the manufacturers/dealers complaints procedures before going too public.