What's going on with my account?

I’ve been a customer for about two years. On 13th March I received a large number of statements all crediting me with the cost of energy used in each month from the start.
And then on 18th March I was debited with a single large amount which was the total cost of all the energy used in the two years.

That leaves my account as it should be, but as you can imagine all this is very confusing. So what has been happening? I suspect it is a a consequence of a (probably failed) attempt to sort out a confusion between my actual postal address and the address shown on the national database (which is wrong because of a lsting showing plot number rather than postal address number).

In addition all my previous daily usage figures have disappeared. And when I looked at the meter readings it said “no readings yet” with a Submit Readings button. But when I clicked on that button it did not give me a place to submit a reading, it just threw me back into the main menu for my account.