I've spoken about this before, although I didn't call it Dark Patterns, I called it "Systematic and Premeditated Incompetence". When I worked for Shaw Cable, and Star Choice Television, (after they were acquired by Shaw Cable) we'd employ any number of "Dirty Techniques" to retain customers. While the company never acknowledged them as such, it was pretty clear what they were up to. At Star Choice, remote customers calling from remote areas on Cell Phones (remote cabins without land line service) were regularly waiting on hold for hours on end. This was 15 years ago, at that time no cell phone could even run an hour. And if by some miracle you, the customer, got through and suggested you wanted to disconnect, well, we weren't "empowered" to do that, we'd have to transfer you, the customer (with another hour or longer holding pattern & circus music specifically designed to encourage you to hang up or go insane) to a special "Saves Team". If you, the customer, at any point hung up or despaired you could be assured that you were still on billing, the company accepted no excuses and took no prisoners...
if you wanted, however, to upgrade or expand your package your call was immediately answered and you were transferred to a priority agent who provided you with swift and prompt service. No upgrading customer ever held for even 2 minutes on a call.
Anyways, apparently the label for this fine behavior is "Dark Patterns", and you can read more about their "tricks" on their website here:
Link: Dark Patterns
Or watch a short youtube video explaining: https://www.youtube.com/watch?v=kxkrdLI6e6M