Duram Paint not the colour on the tin

I bought a 5l duram roof paint to paint a little section of paving at my house. The colour I bought, was charcoal. When I painted the paving bricks, the colour came out blue grey. I took photo's and sent it to their customer care. They immediately phoned me to obtain the batch number, which I provided. Apparently they have checked the batch, and claim that it is charcoal. So I asked the person - Daniel - he has the photo's I have sent him and it most certainly is NOT charcoal, but blue grey. I have YET to receive an response from them as to how this will be rectified. As a result, I will NEVER ever purchase a Duram product again! Totally pathetic, and now I will have to buy other paint to obtain the colour I wanted in the first place.