Remaining balance of my settlement

Hi good day.

How do I get my remaining balance in my final settlement. My previous company told me they will sent in my account the remaining balance of my final settlement on August but until now I didn't receive it. We don't have final agreement about my final settlement only paper that they give me some amount and the remaining balance they will give on date mention I send them message but no once reply to me. They ignore it. And my contract before they will change without knowing my basic salary it's not same in my 1st contract before I renew it my contract. Then when I finish contract my basic salary is less, that's the reason why my final settlement is less in my computation. My previous company don't know that I have copy of my contract with manpower stamp, ministry of foreign affairs  and the embassy. I hope someone give me advice here what I will do. TIA