Green Star Energy

I have been complaining since Dec 2017 that Greenstar is billing me for the wrong electric meter at my flats. They have finally , after months of torment, amended their records I think but have not refunded me any money or given me an amended final bill or any word of apology or compensation for the long drawn out process. They have brojen many promises re contacting me and don’t answer their phone when I try to contact them. An absolutely outrageous situation to be in and an appalling service. In addition their delay has cost me money as I had been unable to switch suppliers in time for a reasonable energy rate. I am just being completely ignored whilst they hang in to my money which they have wrongly taken from my account ( my consumption was much lower than their estimate)