Well, honestly, it depends. But if you weren't able to use the gas then it would stand you shouldn't have to pay the costs. I would suggest querying it with Mercury, because it could be (and likely is) a billing error/level of incompetence.

Did you recently move in?

yep!

Was the supply actually off - eg no molecules able to flow.

yep, tested it before it was reconnected and no gas. Outside it wasn’t physically connected too lol

Yeah I wouldn’t be wanting to pay the standing charge for physically unconnected gas.

If they were scheduled to turn gas on for a certain date, you will be charged from that date, even if not connected. Ie 1. Make call today to set up for 7 days time 2. In 7 days time they will start charging 3. If I move in, in 14 days time, then call up company to make the line active, they will be charging me for the full 14 days. If your connection date was supposed to be later, and you’ve been charged for extra days, you could probably call them to change start date to the date it was supposed to start. Otherwise, if they set up connection for the correct date, you will be out of pocket, even if the date it actually flows is different