I suggest sending a letter before action which outlines reasons why you are owed the amount in question and failure to pay within a set deadline will result in court action.
Please see below a template letter format that can be amended to suit your position.
insert name and address) (insert date)
LETTER BEFORE ACTION
Re: Claim for (insert sum)
I refer to the above matter and to the above sum.
[Then explain why they owe you the amount in question].
I note that, notwithstanding my requests for payment of £[insert amount], in respect of [amount of the debt], I have yet to receive payment. In the circumstances, I am no longer prepared to leave this matter in abeyance and, unless payment of the sum is received within [insert reasonable period of time, eg 14 days] of the date of this letter, I will commence proceedings without further notice.
This letter is being sent to you in accordance with the Pre-Action Protocol for debt claims (“the Protocol”) contained within the Civil Procedure Rules (“CPR”). In particular, I refer you to paragraph 7 of the Protocol, and paragraphs 13 to 16 of the Practice Direction on Pre-Action Conduct and Protocols regarding the Court’s powers to impose sanctions for failing to comply with the provisions of the Protocol.
I therefore put you on notice of my intention to issue county court proceedings against your company for my losses should I not receive payment in full by 4 pm on (insert deadline date ). Should court proceedings be necessary I will claim the court issue fee and statutory interest. Should I succeed in obtaining a judgment, same will be transferred to the High Court for enforcement against you and your company whereby further costs will be added to the judgment sum.
I trust the above will not be necessary and I therefore look forward to hearing from you as a matter of urgency.
Assuming the letter does not produce the desired result i suggest you return to JA and we can assist you with the next steps which may be court action that you have put the firm on notice about.
I hope i have clarified the position.
Thanks and stay safe.