Service availed to provide service to an unit in sez

Respected experts,

Greetings of the day!!
One of my client is providing Road Transportation Services to an Authorised Unit in SEZ. The SEZ unit got certificate from DC for ab-initio exemption from charging service tax on the mentioned activity with name of service providers to him.

SEZ unit had provided the certifcate to my client in which his name is also mentioned. So accordingly my client is not suppose to charge service tax on the same. However, major issue comes in picture now:

1. My client is engaging some other party to provide Road Transportation service to SEZ unit and that Transporter is charging service tax on his bills to my client. Which means, my client will not collect any service tax from SEZ unit but as he had availed service to provide such service. So, can he claim any exemption too? Or can he claim refund thereafter. Just like Form H in VAT

2. If not, than how that balance of excess credit will be settled,as the amount is huge?

Thanks in advance