Many years ago, I had some bunch of muppets in a call centre trying to sell me a telecoms package. I was quite happy with the service I was getting from my current supplier and had no desire to change and told Gonzo & Co as much. They rang three times that week - On the third occasion, I told them a credit card number and/or purchase order would be required so that I could bill them for time wasted (at a rate of $1,000 per hour). The following night, four calls in the space of an hour....
Next morning I tracked down the telephone number for the CEO of the parent company and got to speak to his personal assistant. By lunchtime, the manager of the call centre was ringing with a grovelling apology and the lead muppet was on his way to the dole queue. I didn't get paid for the time wasted, but it felt good to give 'em a kick in the knackers
So.... If you have a problem with service, always go for the top dog - They are in charge, so they should be held to account for the actions of their minions.