Yes I use a lot of 3ds models to and some don't import correctly due to their complexity. Most 3D modeling packages are able to import/export 3ds. However the way they do can be very different.

Have you tried to import this model in pieces and reconstruct (merge) them inside MED or a better 3d modeling software? This would be painful to accomplish in MED I think.

Also your 3d designer could download the *free* Lite-C which comes with MED to test his work or even save it to mdl format before sending it to you. If his models are as highpoly as the one you showed, then its really not a bad idea to have him create a normal map as well as a lowpoly model for you to use in Gamestudio.