Jumbo phone scam - how does it work? (Santiago de Chile)

I first heard of this scam about a year ago, when they called my wife on her cel phone and tried to get her to go to the nearest Jumbo to claim a prize, but asked her to keep talking on the phone all the while. Her battery ran out, so she switched to the fixed line, called Jumbo and they confirmed that there was no such prize.

This was a midweek call, so we assumed this was all about getting a lone person out of the house, or maybe just trying to get her out so they could jump her in Jumbo car park. Then I got the call last weekend, this time calling to our fixed line. On a Saturday.. so bang goes our theory about them trying to make sure the house is empty.

Does anyone know how this is supposed to proceed, if it all goes to the scammer's plan?

Here's how the call unfolds:

Gave his name as Victor Santibañez (presumably changes it every time), on behalf of Jumbo Alto las Condes. He sounds quite educated, and my wife recalled that he sounded like a TV voice, clear and expressive.

He goes on: Your fixed line has been randomly selected, you win a bono of $150,000. You have to go to the nearest Jumbo or Santa Isabel, and recite the phrase that appears in Jumbo publicity. Do you know the phrase? (I guessed, "Jumbo te da mouse" - thank my kids for that one, haha!). No, it's "la compra incógnita sorprende en Jumbo" or something like that. (presumably, if you give the right phrase, he'll know you know it's a scam)

When can you get to the nearest Jumbo? I told him I was busy, would be in the afternoon. "You don't seem very excited to have won something, it's 150,000. What do you think of that?" He said that a couple of times. Then upped the stakes... Also there's some kind of credit deal, a million pesos. And later changed the story yet again: do you know the three daily brands that are working with Jumbo? I didn't catch what he said then, something about buying them as a normal customer (the incognito part) and Jumbo staff will approach you if you win (I think). He asked if I was prepared to be put in the spotlight like that, and again repeated the 'you don't seem very excited' line. The three brands today are Coke, Lacteos Soprole and Claro phone cards.

This reminded me.. doesn't he want me to be on a mobile phone? right on cue he says: can you get to a mobile phone? Now I'm a bit bored of stringing him along, so I tell him I don't use a mobile phone. He hangs up instantly.