Lenovo — Customer support not replying BTC offer

Address:

Chennai, Tamil Nadu

I have bought Lenovo Y50-70 laptop from lenovo authorized seller.I have completed my Back2College offer registration on 14th August, 2015.I have send all the necessary documents required to register for Lenovo BTC offer.But the BTC team neither replying to the mail nor picking up my phone.When I called the customer care they told me that to contact the particular department.But what should I do as they are not picking my phone.