Late payment/ Charges

I have a smart meter and switched to bulb 3 months ago from PAYG plan to credit bulb credit plan. Since then I wasn’t able to pay for my gas and electricity till today when I received an email about the outstanding balance. I now have £500 outstanding balance.
Will my supply be cut off if I top up my balance weekly by £50-£100?
I don’t seem to find a way to contact them by phone or email and on the email that I received today the only thing that had mentioned payment difficulties is directing me to citizens advice.

Besides, for the first day of the month the electricity and gas are being charged way more than usually and I’m not sure if that’s supposed to be happening.

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