For as start I am assuming your in Australia going by Supreme websites  .au   Very impressive rig. 
Firstly I would not accept even if warranty has run out a caravan from new 3 yrs old leaking I would claim manufacture fault.  So put speaker back contact dealership where you bought it and tell them see what results.. Also go to your government website see if they have like UK rules on consumers rights.,  We have in UK   ‘Sale of goods act’  to protect consumers/customers from crap made products  try for tips  www.direct.gov.uk   look for consumer rights .
Now if you get no positive response from either the dealer or manufacturer to put right the damage/problem then tell them you’ll be writing to the national caravan club in Australia so all campers can see the problems you have had with this caravan just put in that you’ve had to have the air con re-gassed and have problems with a leaking roof after only 3 yrs.   Tell them that might kick ass and the put right the wrongs free  of charge, they don’t like bad publicity.  So re-fit speaker then start action.
If no joy at all  then you have to seal the leaking roof if not done already and pull out if its fibreglass insulation and allow it to dry out naturally or use  hair dryer, a pain as it takes time and makes your arm ache and followed by silica gel moisture absorbing crystals  to help take out any moisture present overnight.  Then re-pack with the insulation.
Good luck.
                
 Bob
                
 March 2012