supervisor and manager failed to solve problem

I wanted to purchase power steering fluid, so I asked the attendant for the correct one, & I paid for it. On getting to the car when I open e container to find out it was the wrong fluids coz of color. On return to the counter I requested the correct product. Supervisor came and told me that because I had opened it so I had to take it. Even tho they had told me it was the correct product when I asked. i asked for the managers number which they refused to give me and they called him on their own and spoke in a language I did not understand and they ruled that I buy it. So I bought another container of the then correct fluid and left behind the other one that I was forced to pay for. Both manager and supervisor failed to handle the situation in a professional manner.. That is my money thrown down the drain. I don't think I will be seeking service at that garage again with such ride service..