We're leaving Egg as well
Recently they keep trying to take the full balance off us when we've set the payment option to a fixed amount. First time cleared us out for the month and resulted in failed payments in our curernt account because the egg payment took us right up to our agreed overdraft limit. Further normal payments were then bounced, all resulting in fees and charges.
Egg's attitude on the phone was "tough, that's how it works", and refused to listen to our demands for compensation. Sorry, but that's NOT how it works. We've been with them for years, and it always used to debit what we set it to, and the setting stayed put until we changed it.
The following month, we kept a closer eye on it. Several times we changed it from "pay full balance" to "pay £100", but each time, it got reset a few days later. We phoned them, and they set it for us, and again a few days later it was reset.
In the end, we phoned them up again and paid an agreed amount as a one-off payment, and then cancelled the DD on our account. Despite them agreeing to it, they still sent us a nasty letter when the DD they said they wouldn't take was bounced by our bank, and a form inviting us to set up a new DD - we put it in the recycling.
Used to be good, now a load of pants, and good riddance to them.
Paris, because she doesn't know a lot about pants.