Service tax under rcm

Please advise whether service tax under RCM is applicable in the present case :-

X company supplies materials to Y company using the services of logistics company Z which is an associate of X company. In the purchase order of Y company raised on X company, Y company accepts to pay a fixed rate per MT for freight which X company includes in the bill for supplies. LR is raised by Company Z for transportation of materials from X company to Y company indicating Freight Prepaid. Whether Y company is liable to pay service tax on RCM? If yes, kindly give details of court order, if any.

Thanks

K Venkatraman