If you are totally offhand and unhelpful, they will certainly NOT buy off you again, and more importantly, will probably tell all their friends not to buy off you. It can take years to build a good reputation, but only five minutes to destroy one. As a last resort, it is usually better to accept return of faulty or unwanted goods gracefully, than to argue. If it ever gets as far as litigation the courts usually find in favor of the customer and the lost goodwill, never mind the legal fees, will rarely be worth it. Some time back I beefed that too many web sites didn't have enough words to explain their offers.
Some sites are all pictures with very little copy.
Now it looks like a lot of sites have gone the other direction. In an effort to maximize sales, they put dense copy about all their offers on the opening page of their site. The latest thinking among advertising experts is a page filled with lots and lots of copy is jarring. I don't have time to read all this. It's often better to trim your opening page offers down to just your most essential elements.