Ecom Express — fake weight discrepancy

Address: gurugram, delhi

I am a ecommerce seller who sells through amazon and i was shipping my parcels using Ecom Express. my all parcels dimensions are 12x12x2cm and weights hardly 120 grams, but still i pay for the parcel upto 500 grams, but suddenly after few days of shipping the parcel the ecom express puts an fake weight discrepancy on that and and charges me for 1 kg parcel which is twice the amount i pay for 500gm. i have all the proofs of my parcels (photos, also i can show you my amazon product listing you can match it from there). There is no way to contact ecom express, their official number available in public forums is switched off, i have mailed them 10s of times no reply, but in linkedin sometimes they reply and all they say is we are looking to solve your issue, but even after a month nothing has been solved, and i have to keep paying them extra money for the courier.