Everyone says Walmart, but I work as a lower level manager in a Walmart store as a part time job while I'm in college and it is NUTS what we do for customers. I am no supporter of the store, in reality, and have a lot of complaints about the company as a whole, but we do so much for customers. I'll absolutely agree that it can be hard to find people to help you sometimes, because the stores are without a doubt understaffed (one of my many, many complaints about the company,) but as far as actually taking care of the customer (on the level that I work at) we go above and beyond what most stores could do. I am a customer service manager, meaning I am over cashiers, cart pushers, and service desk personnel. Most of what I do is deal with angry customers, and I can honestly say that we practically give **** away to people just to keep them from raising their voice at the service desk. Sure, we have some wonky return policies that we have to follow, but they are FAR more lenient over all compared to many other department stores.
90% of the complaints I receive are from people who haven't gotten their way on returns, with the other 10% being actual customer service issues (mostly complaints on not having a certain item in-stock, or not being able to find someone to help them - both of which tie in to the "understaffed" problem.)
I type this not as any sort of supporter of Walmart, and base it on day to day experience. If you think the actual CUSTOMER service is bad, you should see the way employees are treated.