I use to be in the industry and would often grab random queries during my coffee break and investigate them. The majority of the subscriptions where legitimate and often consumers where asking to unsubscribe from a single service and keep the rest.
Where I did find people complain about not signing up the majority where from:
* The website signup form that had no verification and double opt in. Was common for users to type in a wrong MSISDN and subscribe somebody else. Industry regulations prevents this now.
* Recycled SIM's : This is an ongoing issue where both networks and WASPs are responsible. In the past networks did not want to give us their recycled MSISDNs as they felt this would give competitors the advantage as to their churn rate. WASPs would also not unsubscribe uses after n amount of failed bills usually due to numbers being dormant for recycling.
* Letting kids play with granny's phone: So many times I would pull the logs to verify that somebody had subscribed on the users phone and then some old lady would confirm that her grandkids had used her phone.
As for the legitimate ones, well people would scream victim when their spouse or employer would find out until I would show them the logs.