Electricity bill

Indeed - I was surprised that they were surprised!

So true! The same thing has happened to us. The only improvement is that the new company has a direct phone for older/vulnerable customers so you can get straight through to a real person. They must be specially picked to be kind and helpful.
With our last supplier, based on their calculation we ended up £800 in credit. I was damned if I was going to give them this as an interest free loan!!
Of course consumption goes up in the winter. It also plummets in the summer but that seems to come as a surprise to them!

I have just delved into this in more depth and it seems that they have not been debiting the original agreed amount, so we are in debt to them owing to a fault at their end. I am on it now! But boy is it hard work getting through to these guys!

It used to be so simple - ah, the good old days!!!

I would calculate, even if it's guesswork, what you think you will use compared to your last home and base your DD on that. You don't have to pay them what they ask because if you use more than your DD is covering you can pay the balance in a lump sum at the end of the winter quarter.

We're with Ovo and you can keep track of your usage online by taking your own meter readings and amend your DD accordingly. I presume other suppliers have this facility as well.