CAO Cosmetics interview questions

I applied as a designer and they asked me normal questions about my experience in relation to the position. Communication was quick and easy with them, I did a design test, and they offered me a position. However...the position they offered me was completely different from what I had applied for and the responsibilities had almost no relation to what I had interviewed for. I thought perhaps they had made a mistake and expressed my concern. They asked me to come back to explain the position a little more to me, but they confirmed that what I would be doing in this position would not be relevant to what I had applied for (and what I actually wanted to do). None of this was discussed during any point in the application process nor the interview process before they gave me an offer. I felt misled and ultimately declined the offer. I feel that they should have been more clear about their expectations in their original job posting as I was genuinely excited to do design work there.