Web Developer Needed - Small Job

I need to hire an OpenCart developer to correct a small problem we are having with response codes.
Please pm me with a quote or request for more information.

Shortly after moving to our new url, we discontinued a lot of old products which are returning the wrong response code.
For instance myoldwebsite.com/4041 is correctly 301 redirected to mynewwebsite.com/4041 . However the response once there should be a 404, not a 200.

I thought the problem was with our host server, however they gave me the following reply;

I am afraid that that we can not further assist you. It is your website that is set to return these codes and we can not do anything on our end to change them.
Please contact some professional website developer who could check the website and set the correct response codes.