I had a reroof done, and I ask the supplier of the roof sheets for a written guarantee. I only got some stupid excuse that you need to apply before you buy the roofing sheets.  I bought Colourbond charcoal sheets from a hardware store in Bellville.  The hardware store refuses to give any explanation, and it is becoming a problem for me.  The roofer that fixes the sheets rightly says that they can only guarantee their labour.  The contractor also says he know about this problem, and that he believes that it is impossible  to get such a guarantee in writing.  The hardware store refuses to give me the details of their supplier.