confused

Hi to everyone here!

I have enjoyed reading all your topics and think this forum is amaizing. From what I have learned abaut the colours finally I started my quest of getting it right this time. However I had a little problem along the way 

After couple of years colouring my med/dark brown hair very dark to avoid the red undertones (which didnt help by the way) I have decided to bleach it and then start again but this time with some more ashy colours in order to get a very cool one (warm doesnt look good on me) . I got to a very light gingery/yellow and decided to go to the hairdresser to cover it with some nice medium ash brown as I didnt trust the home hair colours. This was after a week of puting protein masks regulary and my hair was in a very good condition. When I sellected the perfect colour I was under the impresion that it will be permanent but they have told me that I can only have semi which will be best for my hair and it will stay for longer. I didnt want to be argumentative so I have accept it how they have told me. I had the semi colour and a nice cut (my hair is still left very long) and at the time lovely brown. But now I am very confused becouse after only five washes the colour is scary. It is orangy/brown/yellow at different parts and nothing left from the ashy brown colour I had put at the hairdressers. I phoned them to complain and they said it should not have happened as the molecules of the semi where smaller and more resistant of faiding after the bleaching process ??? I think that this is not correct at all. I have another appoitment with them next week and I want your opinion on the matter. I would like to have a permanent this time becouse I can not keep going to them every two weeks (to much expencive)  .Please help me.

Thank you very much