That is indeed an awesome tweet, thanks, hadn't seen it!

I'm going to say that it looks like a right pickle. By which I mean that the subsequent account functioning and cross bleeding from account to account, and strange activity like the future payments, means it's impossible to just go back to where they started for many accounts. It's hard to see that the bank can ever fully recover - but I guess they can restore where needed and take the losses on the chin, against the future £100 million savings per annum - if things do get unravelled. Presumably many accounts have continued to operate OK.