Re: Not just O2
No it's more akin to complaining to the ticket office, and then being told "Not my fault, mate, we hire the ticket machine from Job Bloggs Ltd. I'm working for <insert rail company here>. Not my problem."
If you bought a product or service from O2, your only legal, financial and customer-service recourse is to them, or an ombusdman of their industry. I don't care WHY they're having problems (whether that's that they haven't paid their bills, that their suppliers are useless, that their contractors didn't turn or, or that heavy snowfall in the Outer Hebrides stopped the consultant coming out today). That's up to their business processes to handle.
My only interaction with them would be via the service they are contracted to provide, and are failing to do so.
In the same way that no court would entertain someone saying "Well, my contractors didn't deliver the goods, so I couldn't give them to the customer who sued me" (they'd just tell them that's their issue, and irrelevant to the case, they are still bound by the contract whoever their goods come from), customer service, returns policies, etc. work the same. They would actually get sued by the customer, and then they would have to sue the supplier to get their money back if that was the case.
You only have to deal with the people you bought the good or service from. You NEVER have to deal with any one of their contractors or manufacturers. Otherwise quite literally you'd be given the run-around between 50 different companies who all do one bit of the work, in order to fob you off as long as possible.
Bought phone from shop and it doesn't work? Take it back to the shop. It's up to them to argue with Samsung/Apple.
Bought phone service from O2 and it doesn't work? You shout at O2. They can blame anyone they like, it's their responsibility, choice of contractor and problem to resolve, not mine.
Otherwise, you'll literally end up being told "Yeah, well, your local mast is run by Bloggs Masts Ltd, who we paid to run it. We don't care. Speak to them."