I'm curious .. How much exactly did they say they wanted to clean and
stain and how big of an area..?

I got down on my hands and knees with some good ol' elbow grease, a
brush, soap and water and a decent pressure nozzle on my hose and
cleaned my front and rear decks and stained them with TWP... I highly
recommnend that one by the way...

Another advantage is you get the satisfaction of knowing you did it
youself and TWP is very user friendly..