Telkom's dishonesty and lack of integrity. Telkom ****ming it's own customers.

So I received a call from the following number; +*** at around 17: 45 on Wednesday, February 1. The guy on the other end inform me excitedly that my number is one of three that was randomly chosen to win R20 000 and the latest Samsung Galaxy smartphone. He's congratulating me no end and ask me how I want to collect my price, do I want the cash through ewallet, Absa cash send or do I want to collect at my nearest Telkom store. He continues to congratulate me, wanting to know how I feel and getting me excited in the process as well. Only to ask me at the end to go and purchase R20 airtime or data in order to qualify for my "reward" and in essence telling me that Telkom is rewarding me for being a valued customer but I will receive my prize on condition that I purchase some airtime or data. I could hear in the background that he's calling from a legitimate call centre. My question is, is Telkom so desperate that they have to resort to gimmicks or trick people into purchasing airtime? For that reason alone, I don't want to be associated with this network because they lack integrity and honesty.