Whink Rust Remover will remove the rust from the leather seats. This is a liquid in a brown bottle. I have not bought any for a long time, but I would think you could buy it at Wal Mart or the grocery store.
Steve, I had a few large orange-rusty looking spots show up on my leather car seat. Never have figured what caused them. Kitchen-type cleaner did no good. Tried Armor-All wipes, and it took a little bit of rubbing, but it all came off. Good luck!