Worked in the Olympic but didnt get proper paid what gov department can i speak to regarding the problem?

Most firms NEVER reply to emails, some clerk somewhere deletes them, saves them having to do something about them. Always write and send it recorded delivery. If no luck contact Boris Johnson, Lord Mayor of London, I am sure he will step in.
UK

EDIT Why Boris Johnson ? because he was involved in the setting up of the Olympics as it was in London. . Beside which he is a very approachable person. He and LOCOG worked together and he was very proud of the workers and volunteers. He can go straight to your employers unlike ACAS or anyone else mentioned.

Send them a letter through registered mail, if you get no satisfaction go and complain to your MP, take all you documents, letters with you, he/she will write to them on your behalf and it is unlikely they will ignore an MP.

LOL at the person above who suggests you contact the mayor of london, Boris Johnson, to get involved in your case - he will just delete your emails like the others. If he had the time to get involved in every dispute about pay, he would have no time left to do his job. So just ignore that comment.

You can either talk to ACAS as suggest by someone else above or alternatively you can go to your local Citizens Advice Bureau to see if they can not only advise you but write to your employer and remind him to pay you what is outstanding to you.

No good approaching LOCOG or any other department; they will (quite correctly) refer you back to your employer.

Much more helpful idea is to contact ACAS, the employment law experts, who handle anything to do with employment queries and problems. They will give you free, impartial and confidential advice. Masses of useful info, plus contact details, on their website: www.acas.org.uk or ring them on 08457 47 47 47.

If you ask them to (but not otherwise) they will contact your former employer on your behalf (free).