I just switched my cell phone provider from Sprint over to T-Mobile. The main reason for doing this is that as a Sprint customer, I never felt like I was valued by the company. The CSRs were horrible: they weren't fluent in English, weren't empowered to help solve my problems, and didn't follow SOPs when trying to fix an issue on my account. Seriously, I'm not the only one who complains about Sprint: Check out The Consumerist's slew of Sprint posts.
Wow, T-Mobile -- what an improvement! I knew something was up when I called to activate my phone and they asked me how my day was going, whether I had any exciting plans for the weekend, etc. Plus, they've done two things on every call: apologize for the inconvenience that my issue might have caused me and thanked me for being a TMo customer.
Apology: "I can understand how not being able to connect to Verizon's network to roam while on the Metro can be upsetting. I'm sure you are worried about missing a call or two, but let me explain how T-Mobile works..."
Thanks for being a customer: "I see that you've been a T-Mobile customer since February 19th. We truly appreciate it and if there's anything else we can help you with, we're here 24/7."
Think about it: CSRs are the part of your company who have the most direct communication with your customers, and often it's when your customers are having a problem with your service. If you try to quickly get them off the phone, are unwilling to help them through a problem, etc, how is that going to affect that customer's feeling about you?
Check out Seth Godin's post on what he feels causes a lot of customer service issues and how to fix them.
One more thing: From a purely marketing standpoint, think about this post. I've just created a free advertisement for T-Mobile. People will read it, will take it as a personal recommendation, and may take it into consideration if they're also looking to switch providers. In Sprint's case, they've just won another person that's ready to put them down as much as possible.
It's all about customer evangelism.