Asking for extra amount after picking up courier from my place

I had booked courier service from dapodi pune to ahilyanagar maharashtra. Courier included 1 bicycle and 2 chairs weightage around 20kg. I ve mentioned all the details on their app and uploaded photographs. After collecting courier they informed me that our courier weightage is around 124kg after packing and were demanding excess amount of Rs 1300 to 1400 more , even after payment of rs 577 has shown on app and 300rs packing charges. I request them to cancel courier service they told me that amount will not be refunded.