Payment taken from my credit DOUBLE amount stated on app

Hello,

Last month (July) on the app it stated that my monthly usage was around £60 (I had been on holiday so barely used any electricity) however Bulb have decided to deduct around £120 from my credit that is building up - how can you possibly justify taking double the amount of money that was stated on the app? People are already going through enough money struggles. Please advise on what to do!