How to claim the amount of an invoice from client who is not paying

My firm (based in Dubai) is owed AED 140,000 for providing manpower services to support catering operations for a Dubai-based business head office in Abu Dhabi.

They have failed to pay my invoice since Sept 2017, we keep chasing them all but management changed and they don't bother to attend any emails or calls.

What I'd like to do is recover my money with late fees and all legal fees. It's quite a long time now. They are a reputed group of companies and it seems they are not willing to pay.

Please note that all documents are in place such as the agreement, invoices, and delivery notes.

Any help or advice is appreciated, please.