I have found that companies thrive on feedback. If you like a product, sent them quick email to let them know, if you have a complaint, let them know as well, but put a somewhat positive spin on it, such as "I have found your product is usually a quality product, however..." Even companies that consistently put out quality products can have problems from time to time, and most will be more than willing to make up for it.
I have gotten lots of for free or money off coupons in the mail in this manner.
Also, don't be afraid to haggle for things, such as cable services. With multiple companies vying for your business, look at all the available plans available in your area, then start making phone calls. Start with the highest price and let them know you have a better offer from company b. Keep working in this manner until you have your lowest price, AND your shortest contract, or even better, none at all.