Inquiry regarding average commission fees for sourcing, customs clearance, and certification agency services

Our company sources products from China for Company A's application, negotiates with sellers to modify them according to Company A's app requirements, and handles the entire customs clearance process. We also act as an agency for certifications and cover those costs ourselves. However, due to exchange rate fluctuations, the financial burden has become so heavy that we are even facing deficits. We are planning to renegotiate our commission fees, but we are reaching out because there is very little information available on this topic. We would like to know what the typical level of trade agency commission is when it includes sourcing, modification agency, customs clearance, and certification.