This is a common mistake I see every time an English speaker tries to speak Spanish, or a Spanish speaker tries to speak English.
- Mister = Seņor
- Sir = Caballero
When in English you would say “Sir, your umbrella”, do not say “Seņor, su paraguas” but “Caballero, su paraguas”. Also, never say “Gracias, seņor” for “Thank you, Sir” but just a plain “Gracias”.