Rust Mini r58 front bumper reinforced bar

Hello I’m new here, not sure if this message in the right place. Have a 2013 mini r58...1 month ago got hit badly by a grittier, well hit twice . Anyway I have cleaned engine out and have noticed some corrosion ,I have pic bellow, it’s where this thing connects to to the other thingy. I have used some atom Mac bilt hamper. Because you mix this with water it’s seems that when I sprayed it couple of days ago got worse. Anyone know what to use to stop rust. Was going to spray some stoner trim shine as that will bring back the metal colour and give a nice finish, but worried , don’t want to cause any more damage

Than you