Foreign exchange

Yes, they can file a fresh case in India. However, if the terms and conditions mentioned in PO, is subject to UAE law, then the case cannot be filed in India. Although, they can go for International Arbitration case.
Or
Before check in Bank for payment acknowledgement, Ask them for the bank audit trail.
That would include:
Their bank name and details including their account number and name
That bank’s “Correspondent Bank” for the currency you are working in.
Both Banks IBAN or SWIFT Codes.
:
Your bank name and details , including the intended account and name
Your bank’s “Correspondent Bank” for the currency you are working.
Both those Banks IBAN and SWIFT Codes to.
The two sets of information should provide you and the international clearing system with a full audit trail. Usually the money is “sitting” in a suspense account as one of the codes is wrong, and either is sitting in one of the correspondent Banks’ as unapplied funds, or been sent back to the originator.