After only a year, the inside of my Tervis mug started to mold. The return process was not easy and I had to pay my own shipping to return the mug! I sent in the lid thinking it also needed to be returned. It took over a month to get my replacement and there was no lid. Customer service said they do not replace lids. I never read not to mail it, so it was obviously an accident. They are making no exceptions. So not only was it a hassle to return the mug, but I had to pay for shipping and now I have to pay for a new lid! Horrible quality and poor customer service!