The main issue is that virtually all new vans have an ALKO type stabiliser built in to the tow hitch. In order to allow the arms of the stabiliser to engage properly there needs to be greater clearance around the towball than on non ALKO fitted tow hitches. Again, virtually all new towbars and hitches are already of this type. If your exisiting towball is detachable then you can easily replace it with a ALKO acommodating type. If it is a fixed swan neck type then you need to check that the distance between the bend and the tow ball itself is long enough to allow the ALKO stabiliser to work correctly. It maybe this is where the delaer has expressed concern.
As mentioned by tohers the squeaks and groans are usually the result of dirt on the friction pads inside the tow hitch. These can be either cleaned or replaced, but if your towball is dirty, greasy, rusty or scored, then the 'repair' will not last too long.