Here's what your friend should do:
1) Find out if you're the only one with this problem.
2) Talk to your superior about this matter. Request that you want to know EXACTLY what's happened to your money, and how long it'll take to fix it. After his lousy explanation, tell him specifically that if you don't receive your payment in the next 3 days, you'll refuse to work until you get it, and express your feelings about the matter (for example, point it it's unacceptable, and you can't believe how incapable those people are). Don't be scared to bump him around a bit (not physically

), he's failed and you have the right. If he tells you you are legally required to work, smash down on the table with your fist and say that it's completely illegal that you're not being payed, and you have the right to refuse to work until you get your payment.
3) Talk to your other co-workers about your discussion with your superior and urge them to do the same thing.
4) If you don't get your payment when you specified, STOP WORKING. Don't even come to work. Just call up and say you're "sick". Get your co-workers to do the same.
5) Companies not paying their employees is highly illegal. You are able to start a process against the company that forces them to pay you within a certain amount of time by law. Do that immediately, regardless of what anyone says to you. It's your right, if anyone disagrees and tries to convince you that what you're doing is wrong, ignore them and tell them the above.
6) Start wearing a Tshirt with your companies name on it and the text "WTF" underneath it

No don't really do that, the UK is crazy and that might result in an arrest.
TheComet