Why did my previous provider still charge me?

Dear Bulb,
I joint you on 23 Aug 2017. You debit me 56.64 pound for both gas and electricity on 24 Aug 2017.
I just found my previous provider Flow energy still charged me 19 pound for gas on 12 Sep 2017 and asked my to provide meter reading yesterday.
Would you please tell me why I now paying two providers at the same time?
What are you going to do about this?
Kind regards
Zhuo Deng

@zhuo We have taken over supply of your meters on the 23rd of August. It sounds like Flow are still charging you from the direct debit. If you are in credit with them you can cancel the direct debit so they don’t take a further payment. Anything you have overpaid you will be refunded once they issue a final bill and you won’t be paying for the same energy twice.