This company charged me twice every month for a fe...

This company charged me twice every month for a few months, and even after multiple reports and long calls with them, the problem is still not solved.

I am currently holding 2 accounts for the same property, (I have no idea why it happened. I have been paying the bill since I moved into the property. And 2 monts later, they sent a mail to register the account. So I called them to register and sent them tenant agreement) linked to the same gas counter. Therefore, I am doubly charged for the same usage of gas.

One has sent me that it has been overdued the period from June 30 to July 31.
However, I have already paied for the period with the other one. Also it has 30.78 credits since I overpaid(paid 89.95 pounds for the period 01.06.2019 to 14.08.2019. Which was supposed to be 59.17 pounds. That means, It has charged 30.78 pounds more)

I am very sick of their customer service.