BAD SERVISE AND ADVISE

I went to Cashbuild Southgate to buy paint. The salesman that assisted us gave us wrong information. We bought Champion Winters Grey Paint and he advised that we get 2 x shadow dye to get the grey I am looking for which we bought three instead. We mixed the paint and did'nt not come to the grey at all. I am quite livid because I have already wasted so much and cannot waste more money buying paint. This is ridiculous that he has staff that gives wrong advise and courses customers more money. I am very disappointed and disgusted in the service.