Unreasonable costs

I moved into a property last year, in August, and the property is using bulb.
I am a disabled person and I am getting into debt due to bulb.
I do not understand how the bills I am receiving are so high.
The property i live in a single bedroom aparentment.
In December my bill was just short of £600.
The month following that my bill was just over £350.
I have put a lot of effort into greatly reducing my usage yet my bills for the months following have been £188.
I have been watching the help and support website for bulb during this time and I have seen that many customers have been complaining of high Kwh usage and find myself in a similiar situation. My Kwh usage is high despite me having my boiler off many nights and not the whole night when it is up. I have changed my sleeping schedule to do this. I also do not use the radiators. I have started using a portable oil radiator in one room for sleep.
Due to the staggeringly high cost of these bills; I have been working to reduce my kwh usage with the intentions of getting things to a manageable level and then discussing with bulb how to pay back through a payment plan; but without consultation or notice I see that bulb took a £175 amount from my bank account which of course I Was totally inprepared for on the account of being uninformed. They usually just take £60.
I used to pay £100 on gas and £100 on electric at a time in my previous property and this would last me several months.
I find both the costs and this action regarding uninformed bills to be unreasonable and I have no idea what I can possibly do to improve this situation. I Worry it’s just going to get worse with the increased rates. In a single bed flat in which I am not using my boiler many nights and do not use the storage I cannot comprehend how the bills I am receiving or how my Kwh usage is so high.

Using a portable oil-filled radiator will be much more expensive than using the central heating in that room - despite the price increases, electricity is still much more than gas per unit.