there could be a system in place that will charge the 100 as soon as more minutes are put in. ha ha ha. imagine those petty a**holes making 20 prank calls about the lack of beer, pizza and toto and then crying like babies when every single peso they put in the phone in the future goes directly to 911.
You bet me to it... yes system to the likes of "prestame fondos". I was about to suggest the same thing. But I would go even further. If there was a real emergency, AFTER the units were dispatched and took care of situation, you could open up a "reclamo" with the carrier, who would check with the system whether it was a real emergency, and if yes, the 100 pesos would be refunded back.