LT26 is one example of a 10 calendar day limit. But the point is, we know companies can move mountains when they have to. They obviously don't feel compelled to.

That's a letter you get as a final notice after previous non-response.

Companies can move mountains yes, but a routine request to cancel a service probably isn't seen as requiring that. Especially since the service contract undoubtedly defines the terms upon which either side can cancel.