I cannot believe it needs replacing. Towbars always rust but they are made of thick enough steel to long outlive the life of the car. The brackets for the lighting sockets do rust however, and are very flimsy. These are easily replaceable without changing the whole towbar.
If it is surface rust you can clean it off and treat it with rust killer then paint it. They are pretty substantial things, I would consider getting a garage to have a look at it first.
If the ball hich is rusty , it may simply unbolt(depends on type).
------------- DS-There's more to life than football!!!