Welcome to JA.
I am sorry to hear about your situation,
Please note that this is not a chat service therefore you may experience delays.
Given this is a debt matter, I suggest you undertake the following steps:
Draft a letter to the letter and at the top of the letter put the following words in big bold print LETTER BEFORE ACTION
Within the letter describe the agreement and most importantly why the amount in question is owed to you.
The letter needs to demand payment within 14 days and say that if they do not pay you, you will issue county court proceedings against them. Further in the letter inform the person that if court proceedings are commenced you will seek interest on the amount owed.
Send the letter via post(recorded delivery and email too)
I have attached a template for your consideration.
Hopefully the letter will compel a response from the debtor very quickly.
Assuming the person does not respond to the letter or a resolution is no met within 14 days from the date of the letter I suggest you consider commencing court proceedings using the link http://www.moneyclaim.gov.uk.
A user guide for the link to assist you with the court procedure is noted below:
If you win then once you have the CCJ from the court the defendant has 14 days to pay in full. If they do not then it gets registered with the credit agencies after 30 days. You can also enforce the CCJ with the county court bailiffs or transfer the debt to the High Court for a small additional fee assuming the total amount owed is at least £600 and you can use the high court enforcement officers who have greater powers than county court bailiffs. The transfer fee is added on to the debt and payable by the defendant.
You may find they just pay you after receiving the letter before action – hopefully they will want to avoid litigation.
I hope i have clarified the position.