Groaning noises when towing

Katia

Our Lunar Loxwood (Quasar) has developed very loud "graunching" noises when being towed - it is fine in a straight line but any change in camber, roundabouts and bends causes this problem.   Having read members' comments on this problem we have tried all
methods of cleaning pads and towball without success.  Our Caravan Supplier is going to change the pads to try to rectify this problem but states that they hear this problem almost
every day!  He says that Alko are not interested as we have found too. Has anyone any other ideas please and surely this should be addressed if so many people are affected. Would be grateful for any help you can give.