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 = Señor
- Sir = Caballero
When in English you would say “Sir, your umbrella”, do not say “Señor, su paraguas” but “Caballero, su paraguas”. Also, never say “Gracias, señor” for “Thank you, Sir” but just a plain “Gracias”.