I am sory to read of your problem, well actually its not your problem, its the dealers. The dealer has a legal responsibility to under the Act 1979 and other relevant legislation to only supply goods that are as described, fit for purpose and of satisfactory quality.
Clearly, if through normal use, part of the caravan damages another it is not fit for purpose, and therfore dealer is totaly obligated to you to either replace the caravan or offer an effective repair. If you are using finance, advise the lender of the problem and ask them to sort it out. If you have any truck from eitehr the finace house or the dealer, refer the matter to trading standards.