NimbusPost Pvt Ltd - Charged against weight Descrepancy

We use Nimbuspost as our shipping aggregrator. Weights were given as suggested by their employee. The conversations and chats are backed by proof. Then there are disputes over weight which is promised to us that it will get resolved in our end since weigths were as mentioned by the Account manager. After ** days suddenly disputes are solved against us and we are charged from our remmittance more than * lakh ** thousand rupees. No one from the company is taking resonsibility from this neither they are responding.