airtime

Q: If a person loads airtime on his phone and receives some free airtime, can this free airtime be used to enter competitions (e.g. competitions found on food packets, etc.) via SMS or phone calls?

Q: Is it permissible to take extra amount on mobile load. Also is it permissible to take extra amount on utility bill payment. Explanation: Today we see every mobile load shopkeeper takes 1 rupee extra on mobile load. Like if we want to load 30 rupees, loader gets 32 rupees and loads 30 rupees. Will this extra two rupees be sood or not?