Green Star Energy

I have been trying, for over 3 months, to get GreenStar Energy to correctly update my address details in the gas meter database so that I can switch to another provider. I first made contact in February 2018, and have made dozens of calls and send numerous emails, but cannot get them to do so. Complaint number 57011 was closed out by GreenStar Energy yesterday and an email send confirming that the database has been updated, but my new energy provider confirms that it is still incorrect. I cannot make any progress and am being repeatedly lied to - they claim to have updated the database twice already, then advised that they had no record of my calls. I believe that my details have been deliberately corrupted on the database to prevent me from switching, as they must have been correct when I transferred to GreenStar.