iskin revo causing screen to freeze - anyone had similar problems?

Bought 2 new iphones for myself and hubby for Christmas - has been working fine wiht no issues - until yesterday. Had ordered iskin revo for both phones, they arrived yesterday, put them on, looked the part, but then about 5 hours later I lifted the phone, set the alarm to get me up for work, then the screen froze, could do nothing but reset it, then when the alarm went off this morning again the screen was again frozen. My husbands iphone also froze twice last night, so as this was the first time this had happened since we got the phones 2 weeks ago we put it down to the addition of the iskin.
Called Apple technical support today, was told that Apple don't support the iskin revo as they don't make them, but I advised that I bought them as they were avalable to purchase through the Apple store and received 5 stars. After the assistant checking out my story and confirming that they were for sale on the Apple site for the iphone, I was told that it must be causing the iphone to overheat it was a computer and needed air to circulate around it and maybe I should return the case! The iphone was not warm to the touch after taking it out of the case, so I don' think its overheated. I had been using an isock up to now and had no issues.
Any thoughts?