You still don't indicate your driving usage, but it sounds as if you drive mostly in town. Any MB with a properly functioning a/c can make a Polar Bear scream for mercy on the highway.

The component in any a/c that largely determines that systems cooling capacity is the condensor. That is why I recommended a parallel flow condensor. There is no room to fit a LARGER condensor, but the Parallel Flow is a more efficient condensor TYPE.