According to the screenshot the charges have reduced your large credit balance to what is still a large credit balance. I think @meldrewreborn was seeking some correspondence that clarifies why you are in huge debt. There is no mention of debit. Perhaps you have something pertaining to the charges levied on 4th March.
I'm an Eon Next dual fuel customer with no particular expertise but have some time on my hands that I am using to try and help out a bit.