Incorrect Buy Shipping Adjustments

Hi All, I'm shipping products from Singapore to the USA using DHL through Amazon Buy Shipping. Since April, I've been receiving unexpected "Adjustment" charges.

From January to March, I shipped the same product with the same dimensions and weight, and the adjustment was only $0.85. However, starting in April, the adjustments have skyrocketed to $90.62 per order. A jump from $0.85 to $90.62 is a massive difference, especially considering nothing has changed with the shipments.

I’ve contacted Seller Support multiple times, but they keep copying and pasting the same response, claiming that incorrect dimensions and weights were entered, and that DHL charges based on the actual dimensional weight if it exceeds the base weight. They also say the charges are determined by the carrier and cannot be reversed.

The adjustment fees per order are now ranging from $90 to $200, and I’m losing money on every shipment. So far, I've lost around $3,000 in total due to these adjustments.

How can I properly dispute these charges? Seller Support is not helping, and I am desperate for a resolution. Any guidance or assistance would be greatly appreciated.

Thank you!