There used to be many places that would refill bottles but having been down that road, with old scales, weights and blowing off. I would never do that again. bottles should have no more than 80% LG, or when you turn on the cooker, it could spray liquid gas which is lethal. I've been there and done that years ago.... scared me almost enough to lose weight.
Unless technology has moved on and I am talking out of my botty bits again.