It would be dependent on what repair had to be done. Usually, they would repair the part needed and ship back the unit you originally have. If, for some reason, the part cannot be replaced or repaired, they would send a refurbished unit in its place. That is what most manufacturers will do. Usually, you will not get a new unit as a replacement.
The only exception would be if one was able to do an advanced RMA. Generally, you would pay market price + S&H for a new unit. The unit would arrive next day and defective unit would be shipped back using the same packing materials. Once they received the defective unit back, they would credit the market price minus S&H.