I had this same thought when I watched the segment the other day, and I've had the same questions with other Marketplace segments. At least with what they talk about, they give no indications that they follow a proper statistical approach and account for market size, sample selection, etc.
That said, marketplace has put pressure on companies and governments for action in other cases, so I suspect they are a net positive for consumer protection in Canada. So even if the stats are bad, if the over dramatic format helps push right to repair or other consumer protection, it's likely still a win. Just would be more compelling if it was a proper analysis or indicated a proper analysis took place.
I actually did a bit of work on the receiving side of one of their segments once, about a runaway cell phone bill, although it was primarily tackled by another engineer. Turned out it was a third party app the subscriber had downloaded that didn't handle permanent failures in the email protocol for attachment size, so it would sit in a retry loop to send an email while the phone was on. As can probably be expected, standard support wouldn't be able to figure something like that out, and it would die inside telco support. A little embarrassment from the CBC and the right people took a look, the app gets fixed, bill credited, etc. (This was before phone would really indicate what apps were using data).
*My views are my own, and don't represent any position of current or former employers.