Richy
I have been owed money that I knew I wasn't going to get, the second time I kept pestering and got it. The first one I started off with a money claim online and it then ends up in court, I got back half of my claim.
The problem with being the claimant is that the person you are trying to get the money off is within their rights to have the hearing somewhere to suit them and you have to turn up where they decide.
I wouldn't let this go I would be doing it online - they are ping you about and if you can prove that you are owed it and have the evidence then they should be paying it.
Have you got copies of all correspondence, emails, paperwork, invoices, can you say when you contacted them by phone.
I would send a letter recorded delivery telling them you want full payment in seven days or it will be going to a small claims court!
Rob