Offer from a mobile telephone service provider

I've been listening to radio of late and there's this ad that first impressed me. One of the mobile phone service providers has an offer that says 2000 free minutes. For two years. To any mobile phone of the same network.
First time I heard it I was like wow, that's a super cool offer.
Then after hearing it for 2-3 times, I decided to do the math.
To enjoy the full benefit, one can talk for 2000 minutes in 2 years.
Which is 1000 in 1 year.
Breaks down further to 83.33 minutes a month.
On an average that's 2.77 minutes a day.
Now, does that look like a great offer?
Hell NO.

I mean to say, where is the economics or even maths?

I got this offer in the mail last week.
Basically, it asks me to buy CLOTHES for Rs.100,000.00 (over 3 months) so that I can get diamonds worth Rs.35,000.00.
Or...
to buy CLOTHES for Rs 30,000.00 (again over 3 months) to get diamonds worth Rs.8,000.00.

If you are someone who buys clothes for this amount, are you really gonna be interested in the 'free offer'? Wont you, like, just walk into the jewellery shop and pick up the jewels you want?

Or, if you are someone who cant afford jewellery and so are likely to find a free diamond offer tempting, then again, are you someone who can afford to buy CLOTHES for that amount?

So someone please explain to me the logic behind this "OFFER"...