you have to pay back in swiss francs
Utter rubbish. You should stick to shopkeeping (even though it does make you tired).
As they are UK based they can opt for bankruptcy
That's certainly an option. But a better first step would be contacting the bank in question and trying to work out a mutual agreement. If the bank is offered more than it would get if they declared bankruptcy, it's hard to see the bank turning that offer down.