My suggestion would be to get the 'Jeep Connection' type. My Brother In Law had it fitted to his 2011 320d when he bought it< I seem to recall the price being around R5k at the dealers. The hitch can be removed when the towbar is not being used and there was no cutting involved.
The Jeep Connection also plugs into the exsisting harnass of the car, so your ECU knows when you are towing and adjusts accordingly. He uses his car to tow his Penta Caravan, and it really is a pleasure, no hastles.
You can also buy the 'Goose Neck' type from the dealership, but they are more expensive, around R9k. My Father in Law had a aftermarket one fitted for R3.5k also with no cutting to his 2007 325i with Sport kit.