Stained Mattress

I brought a mattress at the The Mattress Warehouse, it was supposed to be brand new and it came with a stain and when I complained they said that when I signed for delivery I was accepting that im receiving it in good condition. But I did not know that it had a stain on because I did not open it right there & then. I received no apology, from them which means that this is aceptable. Under no circumstances do I find it acceptable considering that it was brand new. I strongly do not recommend. Im actually so annoyed.