Colour not matching

I bought 4 20l buckets of Breakthrough paint. We started painting and the colour seemed very different to the colour chart but I nevertheless liked it and we continued using the first 2 buckets. When we started on the third one however, the colour appeared completely different to the first 2. It was not even close but was an earth colour as opposed to the grey colour of the first 2. The paint batch numbers were different for the respective pairs. I called. Builders Warehouse who referred me to the paint rep at Builders who then put me in contact with the regional boss located in PE. He then moved heaven and earth to find me some paint from the original batch and then sent me the 2 he found plus one more by courier. The service was outstanding however I would think twice about ordering this paint again. The actual quality of the paint is good.