One of our US customers is quite satisfied with the quality of our ZT100 rotary latch which made of durable materials, wear-resistant and anti-rust.And he has placed a repeat order with increased the quantity.

Now the rotary door latches are ready to ship, but the shipping cost has doubled compared to when the customer placed the order.

We have reached out to the customer, hoping they can cover the additional shipping cost. The customer did confirm payment on Alibaba but has not completed the transaction. We have tried various methods to contact the customer but have not received a response.

Is there a better way to handle this situation?