Final Settlement Due for over 120 Days company not replying

I am yet to receive my full and final settlement (salary for the last month worked) with my ex-company. I quit on the 31st of July and still no update on the payment. I've been running back and forth, exchanged countless emails with false assurances that things would be settled but still no avail. A few colleagues have ended up sending wind up notices etc, to the company and have instantly received their payment. I even sent them an email saying I would take legal action but that hasn't helped either. Not a large amount (30k), therefore worried about legal expenses. How should I proceed?