Hard water, rust stain removal advice

ban25

Hi guys, I was on vacation last month and when I returned, I found that a rusty pipe in the garage had leaked water down the passenger side door of my silver 370z. It had been waxed, but when I washed it, the stain persisted. Needless to say, I was pretty unhappy!

Anyone know how to remove the stain safely? I've heard that a solution of vinegar and water can take care of it. There's also a product called 'Rust-Off' that might do the trick. My main concern is to remove the stain without damaging the paint

Thanks in advance!