Vodafone's Unreliable Customer Service and Constant Plan Changes

My issues with Vodafone's customer service never seem to end; they say they will call me back, but they never do, and they change my plan without giving me any prior notice. I've grown weary of making attempts to get in touch with them, and they don't appear to get weary of staying away from me. I have made the decision to terminate my subscription; however, they have not yet responded to my request. It is unconscionable for a company to take such a slack attitude toward their work; they have truly tested the limits of my patience!