Motorhome windscreen seal leaking

AandJ

Our motorhome windscreen seal is leaking when it rains heavily. Water runs off the roof around under the curve over the joint and onto the windscreen seal. A wet patch then appears above the post between screen and door in the drivers side top right. Can
this be repaired with sealant as read if we have a new seal fitted the windscreen may break and seals are not covered by the insurance. Windscreen also not covered if broken when replacing seal. Can anyone recommend a e sealant 

thanks