Bind a datapower certificate to endpoint on a client

I have a client server talking to two different endpoints that are secured with datapower certificates. The client server is unable to bind the correct certificate to one of the endpoints, it sends the certificate for the other. I have a webservice that needs some code adding so that when it receives a request to contact one of the secured endpoints, it binds that request to the correct certificate. What is required is for someone with the necessary expertise takes my existing webservice, and add the code required to bind the correct certificate to the appropriate endpoint. The webservice currently contains VB code, although there is no specific requirement that the additional code be basic.