Tata Sky — Luring the innocent customers in unethical way

Sir.
I am an Tata Sky subscriber having id [protected].
A few weeks ago I had received a call from Tata Sky abou an offer of some channel for 15 days free trial offer. The whole conversation was quite vague. Not disclosing the full details.
They did not mentioned that after 15 days the offer will automatically converted in to chargeable scheme. They started the said channel and made it chargeable after the free offer period. Why they lure the innocent customers in to their gullible sales talk ? Thus they are cheating millions of customers and making a huge amount of money very unethically.