They'll ring you three times a day when they want you to sign a contract. In fact, they won't even ring you themselves, they farm it out to third party 'partners'.
When my contract with O2 was up a couple of months ago, I was getting an average of three calls a day, trying to talk me into a new contract. It doesn't matter if it's 7am or 9pm, they'll call.
Turns out that getting unsolicited marketing calls from companies who your phone network gave your details to is an opt-out rather than opt-in service.
There is a thing called the Telephone Preference Service, which you can sign up with to STOP your number being given out. I only found this out after six hours of phone calls to O2, heaps of emails and a Twitter campaign; where I was simply trying to get my PAC code.
To get through to O2 on the phone is almost as difficult as getting the opportunity to compete in the Olympics. When they think you'll sign a new 24 month contract, they'll call you non-stop. When you've decided to leave? They're nowhere.
I was on the phone earlier this week to them for four hours without speaking to a human. They kept me on hold until their offices were closed. And their 'online helpers' told me to wait twenty minutes, before disappearing indefinitely.
When discussing my O2 woes with a friend this week, he said to me, "I have never had a problem with O2, until I wanted to try and end my contract. Spent about two hours a day for a week on hold. Was a joke. In the end I gave up, so I guess they won."
And that's what happens. We get worn down by the impossibly impersonal nature of big companies, and they get their way.
But not this week! I was determined to hold O2 accountable for the phone call harassment from third parties, followed by my inability to get a simple PAC code.
I continually called them on the phone. I repeatedly tweeted them, desperate for help from a company who, over many years, I have undoubtedly given thousands of pounds to as a loyal customer.
But nothing. O2 tweeted back a few times, but wouldn't commit to a phone call or help in any way. My emails kept bouncing back with automated responses. I was getting nowhere!
I started a Twitter hashtag, #HeyO2PleaseGiveDanHisPACCODE - which caught the imaginition of my friends, strangers, and eventually freelance journalists, who began to join my cause.
We pushed on and pushed on over two days; and eventually their web-team tweeted me a direct message with an email address to contact.
Is it really this hard to get a PAC code?
The next day, I sent them a second email, offering to round up some volunteers to work in their phone centres, as clearly they were struggling. It is my opinion that a giant phone network should have at least three people working in customer services.
And then eventually, they called me.
Of course, I was in the midddle of a film shoot, but I decided to prioritise the phone call; because getting O2 on the line is as rare as getting a date with Scarlett Johansson.
"Uh, we got all your emails and tweets" said the woman on the other line. And then something truly incredible happened: she gave me my PAC code.
We all spend hundreds and hundreds of pounds a year on our phones. Is it too much to expect to be able to get customer services on the phone? Or are we only permitted to harassment from third parties?
As for those third parties. Here's what O2 explained to me:
"I'd like to inform you that from time to time our customers may receive calls from sales and marketing companies selling a variety of things including mobile phone upgrades etc. This is not illegal providing the calling party are following the correct guidelines set out in distance selling regulations."
To opt-out of these marketing calls, O2 informed me that you can register with the Telephone Preference Service. As has been reported widely in the media, success with the TPS is not guaranteed. Once your phone network have shared your details, there's no guarantee of your privacy.
So now I start a new adventure, on a different phone network. Will things be any better? Will they answer a phone call before my next birthday? Who knows, only time will tell.