Tell your friend not to pay money to get his own money back, he is entitled to it.
A strong worded letter stating your rights (do research and provide applicable quotes form the certain acts) should do the trick.
Tell them why you are writing the letter, explain why you are owed your money, point out how they are breaking the law, and explain you keep getting the runaround, and tell them you wont be afraid to take it further to the certain courts etc. send the managing director or the owner a carbon copy or the regulating body (IPAV). Let them know you sent carbon copies in the letter. Send it by registered post so they cannot claim they didnt receive it and follow it up with a phone call. If he gets fobbed off again, tell him to call and ask to speak to someone higher. If he still has no joy from that contact the IPAV and ask them the best course of action also IFSRA may help him.
Only use the debt collectors as a last resort.
If he needs help writing the letter give me a PM.