Hi, this is Jim, thank you very much for the question - I will do my best to resolve this for you today.
Yes, you have proof he said he would pay you which you can rely upon if you have to make a small claim against him.
I would recommend that you send him a formal letter before action to demand payment within 14 days and say that if they do not pay you, you will issue county court proceedings against them. See attached template as an example of what to say. Please let me know if you cannot see the letter which I have uploaded. You will need to tailor this letter to your situation. I presume you know his address. If not then a tracing agency can be used, most offer a "no trace no fee" service. You can try these if you need to trace him :
http://www.bnhassociates.com or https://www.candlinvestigations.co.uk
You will need to register at www.moneyclaim.gov.uk so that you are ready to issue the claim in the event they dispute the claim and do not pay you. The website is very user-friendly and you would not need a lawyer to use the money claim site. Claims with a value of under £10,000 are classed as a "small claim", so legal costs are not recoverable and the matter may be dealt with on paper by a Judge, not at a hearing. A hearing may be necessary if the court thinks that oral evidence is required to dispose of the case.
You would claim the sum for the loss, the court issue fee (£60 based on the claim of £525) and court interest which is 8% calculated on a daily rate from the date of loss to date of court judgment. The site allows you to calculate the interest and add it to the claim.
If you are on a low income or have low savings (or in receipt of benefits), you can ask the court for a fee remission so you do not have to pay the court issue fee.
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 if he still doesn't pay despite the court judgment.
You may find they just pay you after receiving the letter before action – hopefully they will want to avoid litigation. I hope this helps - please feel free to ask me anything else.
Have a good day,