I'm glad I'm not the only one facing this problem.
Since yesterday morning, 4 channels that I've paid for (610, 627, 762, 765) as well as pressing the yellow button on the remote shows a 'Box not receiving signal' message for both my HD set top boxes.
I called the Tata Play helpline and rebooted the set top boxes, did a master reset (and even did a software update from my end), but the problem persisted. I was then told I would need to call a technician for which they would charge Rs. 200.
I politely explained the helpline person that this problem is not from my end and it is clearly a signal issue (either with the common dish on the terrace or from the Tata Play back-end) and so I should not be charged. He said that he was only following protocol and I have to pay the money for the visit. I simply disconnected the phone and removed the 4 non-working channels from my pack.
I then directly called the technician in our area and he said that the helpline people are useless in such matters. He suspects there is a problem from Tata Play end (probably some updation work going on) and he told me to wait for 3-4 days. Hopefully things resolve by then.