Staff cleaned in front of us before movie was over

Was watching a film (it was Guardians of the Glaxy, a Marvel film, which means there is still more to watch after the end of the credits), and the credits has just started rolling when the cleaning staff came and started cleaning in front of us so we couldn't see. When we protested, we were answered with dirty looks and disgusted clicks. We should not be treated this way as paying customers. I will not go back to this cinema.