Adding a new bank account

I’m unable to add a new bank account to my 2 existing accounts. This is the method I’ve tried:

From home, click on the “money” tab on the “all” tab use the blue button “add account” select “internet payments” and a new screen is opened up in order to put in payment provider etc. select blue button “save” - pauses for a couple of a seconds on then goes to the “Whoops- something unexpected happened page” (as an aside I've tried clicking on the contact support button shown on that page and nothing happened.)

I’ve managed to add and remove a bank account before (about 2 weeks ago), but no luck over the last couple of days. The error doesn’t seem to be limited to internet payment as I’m unable to add a normal bank account either.

As I'm only an intermittent user this might well be finger trouble on my behalf!