Disappointed/dissatisfied

I went there today I asked the person on cosmetics about the Maybelline super stay special which was going for 150 of which she said yes they still have the special,so she helped me with finding the color and I got 2 when I got to the till it said 600 then I told her but the special is ending today then she said no you can take Rimmel instead I thought they will find a way and give me for 150 each since it's the last day of the special but both the supervisor and cashier just stood there and looked at me,I was very disappointed shame coz I first asked and she agreed but when I go to the till she acted like she was not even the one helping me