warranty means nothing

ever since I've purchased my phone it's been giving me problems , I've taken it to Samsung custom care on numerous occasions, they told me that they will sort it out and I insisted that its still giving me problems . The other morning I got up and noticed that there are purple ink like stains in the screen and it started spreading through out the phone screen so I took it back to Samsung and now they tell me its a physical damaged and that they have to get and answer from the Samsung head office , since buying the phone I've had nothing but continuous problems and it was no physical damage because I place it on the head board thereafter went to bed , after waking up in the morning I notice at it gave me problems and now they give me stories about sorting it out , they do not live up to warranties and it means nothing to them because they continue to lie . I will purchase another Samsung again.