Who owes me the money / what to do next

Hi
I wondered if you could help me with some advice on the best way to go about recovering an overdue payment. This was a web job I got through a contact of mine for several thousand pounds. The first half of the amount was paid while the job was in progress. Two payments of £100 or less were made after the job finished but the rest of the second half has never been paid and is now almost a year overdue.

Now the guy I did the work for has a limited company and I invoiced the limited company, but when I look at companies house the company seems to be 'dormant', ie there's an entry from last year saying 'ACCOUNTS OF DORMANT COMPANY MADE UP TO XX/XX/09', does that mean anything? Also with the three payments made, the original 50% payment came from someone listed as a director of the company, the second came from the girlfriend of the guy I was working for and the third payment was made via paypal to my original contact who then made a transfer to me, is any of this significant? I should also note I never went to any offices or anything like that, the initial meeting was in the guy's home and I think it's basically a one man operation.

The other thing I should mention is that I have nothing on paper / signed setting out the amounts, etc. but I do have an email where he acknowledges the amount owed.

If anybody has any advice on the best way to proceed that would be great. I've telephoned multiple times and recently sent a special delivery letter asking for payment plus fees and statutory interest which was signed for but got no response. I did speak to a debt collection company and they said it was too small a debt for them to take on, but the two things he stressed were the 'dormancy' of the company and the importance of establishing who owed me the money.

Any help would be much appreciated

James