Certification of Ethiopia invoice chamber of Commerce

Our company is in Shenzhen. In order to facilitate the collection of foreign exchange, the company has registered a Hong Kong offshore company. Now there is an Ethiopian customer who signs a contract with a Hong Kong company, and the payment is paid to the Hong Kong company. The goods are exported through the customs declaration of the Shenzhen company. Now we encounter the problem of invoice authentication. The Shenzhen Council for the promotion of international trade only accepts the invoice certification of Shenzhen company, and needs to provide the contract and report However, the amount of customs declaration of our Shenzhen company is much less than the amount actually paid to the Hong Kong offshore company by our Shenzhen company. Therefore, we hope that the unit price and amount signed by the Hong Kong offshore company and the customer will be certified by the invoice. What can we do in this situation?