After several years of being with a particular mobile phone company (I won't be specific, but think of a number between 2 and 4), I decided to change to a different provider. This was due to being able to get a much better deal elsewhere, and because of a change in the existing T&Cs.
Firstly I had to brave the hard sell when I asked for a PAC code. Then, I was informed about some unfathomable charges related to me leaving. These probably would have been fathomable, and may well have been reasonable, but since I could barely understand the person at the call centre, it was hard to know.
Then, two days later, I was phoned by 6÷2. They were offering me twice the minutes, twice the data and a free phone, all at half the price of the existing contract. This was apparently because I have been a loyal customer for 4 years.
To be honest, I would have rejected their offer even if they had been offering to pay me cash. It should not be necessary to have to threaten to leave in order to get a better deal. Good deals should be offered proactively, and should reward customer loyalty. No wonder Three (doh!) keep coming bottom for customer service.