How do I switch bank account?
Make sure there is a current account switch guarantee with your old and new account.
Open up a new account.
Pick a date for the move and the banks or building society do the rest.
What if if goes wrong!
Here is the best defence, after all, prevention is better than the cure!
Get a name of someone in your old and your new branch that you can ask for personally before the move.
Tell them both that if it goes wrong you will phone them to fix it. If they get it wrong you can ramp up the pressure on them. Call 5 times a day until it’s fixed. After 1 day you can complain with impunity.
You can also run your old account until you don’t need it.