When I encounter unsatisfactory services or products, I just chalk it up as a learning experience. Legitimate complaints help everybody in the marketplace.
Complaints help prevent unnecessary regulation and inferior goods in the marketplace.
They also alert businesses to product quality, service and distribution problems. There are legal time limits, depending on the situation, so act quickly. Always go to the seller first. All good businesses recognize a valid complaint as an opportunity rather than a bother. Be sure you are dealing with someone who has the authority to rectify the problem.