Air Con Trunking Leakage problem

[Imaa 0]

Do any of you has face problem of aircon leakage around their aircon trunking area? Its 'perspiring' causing leakage most of the time from the trunking end and leak down my walls. 

This trunking run across my master bedroom door towards the master bedroom toilet.

Called our installer and they came down thrice together with Mitsubishi technician and gave me the conclusion that my unit is more humid than the rest causing this to happen. 

Feeling very frustrated that they are not doing anything to solve the problem and the leakage just doesnt stop. 

Some advise pls..