CoralTech Gas Check

Just got a bill from a company called CorellTech who apparently checked the gas in a place I rent out?

Never heard of these people? Are they legit? The bill 450 CHF for what?

Anybody else had this in VAUD?

Posted this weeks ago? But nobody has replied? Have I been scammed?

Did try calling the water company, who told me it was official? But why has nobody commented? Is this some sort of optional check I could have just avoided.

Can't CorellTech explain you in which circumstances this check occurred, who ordered it ?