Bests & Worsts Reviews from Amazon

I love the glass, absolutely love it. However, I have had a issue with the glass, becoming fogged or marked kind of a white opaque where my coffee line comes to. I followed the directions to return the first 2 glasses as requested by the company, as the other 2 were still OK, and as I said I love my glasses and did not want to do without them all. I thought it may only be two of the four which may have had the issue. Well, now I have 2 more (which makes all 4) with the marks and I have never heard back from Tervis to replace them as the are to have a lifetime guarantee. I would gladly purchase more, if the company stood behind their product, and replaced the now 4 glasses.Is this too much to ask? I have sent a second email to them and nothing. BUYER BEWARE!.