Thanks for your patience. If you are genuinely owed that money and it was due to you either under contract or formally promised by the company, then you can pursue them further for it.
Therefore this potentially amounts to an unlawful deduction from wages, which is made illegal under the Employment Rights Act 1996.
In order to try and resolve this, the employer should be contacted in writing, advised that this is being treated as unlawful deduction of wages and ask them to pay back the money within 7 days. Advise them that if they fail to pay the money that is owed, legal proceedings could follow.
If the employer does not return the money as requested, the following options are available:
1. Employment Tribunal - the time limit to claim is only 3 months from the date the deductions were made. To make the claim, form ET1 needs to be completed and submitted - you can find it here: https://www.employmenttribunals.service.gov.uk/employment-tribunals
2. County Court – this is an alternative way to claim and the advantage is that the time limit is a much longer 6 years and is usually used if you are out of time to claim in the Tribunal. The claim can be made online by going to: www.moneyclaim.gov.uk.
Hopefully by warning the employer you are aware of your rights and are not going to hesitate taking further action they will be prompted to reconsider their position and work towards resolving this.
I hope this has answered your query. I would be grateful if you could please take a second to leave a positive rating (3, 4 or 5 stars) as that is an important part of our process and recognises the time I have spent assisting you. If you need me to clarify anything before you go - please get back to me on here and I will assist further as best as I can. Thank you