Truth is, the customer is always right! If I don't like the service I am receiving I should be able to demand at least what I was told to begin with--rather or not it was someones mistake that promised me such service. However, with the way things are now, a customer doesn't have much to bargain with. Quit buying from company A, to only find out that there are no others out there offering service, or if there is, no other company is any better at customer support, quality control, etc...
All companies should do a better job at taking care of their customers, and with that, all companies need to better train their CSR's, so that they don't do or offer something that ends up not being right, OP's situation as an example of that!