They don't reduce less than R150 fines, also if you challenge the procedure (in court) by not paying admission of guilt fine (IE you plead not guilty) you can face possible jail time or a incredibly large fine, don't understand why but that is what I heard from someone I know who tried it.
True but in cases where the images are incorrect they are supposed to withdraw the fine. Instead they sometimes try their luck by still sending a reduction.
In order to challenge this you must send in a written representation asap. Then the matter gets resolved before going to court.