Inferior product and not honouring warranty claims

Eva Last does not honour their guarantee on products. Installed this Eva Tech Infinity board with a 25 year guarantee product and after 3 years it has discoloured so badly that a brown plank is almost white. Claim was lodged via their website. I get ignored on emails and the attempts at trying to help me with this claim is laughable. R200k worth of decking (not even including the cost of installing) now means nothing. This is also a regular problem with other clients as well.