Balayage went brassy after 3 weeks — is this normal fading or did my stylist skip something?

Got a balayage done about 3 weeks ago, paid £165 which felt like a lot but the day I left the salon it was genuinely perfect, this soft ashy caramel exactly like my inspo pics.

Fast forward to now and it's gone properly orange. Not subtle warm, like actually brassy, especially around my face. I haven't been swimming, I don't use heat much, washing maybe twice a week with whatever shampoo was in the shower (ok possibly that's the problem, it's my boyfriend's head and shoulders lol).

Friend says I need purple shampoo, another friend says purple shampoo is for blondes and I need blue because I'm more caramel/brunette?? And my mum reckons the salon should tone it for free because 3 weeks is too fast to fade.

So basically: is 3 weeks normal for toner to wash out, would the salon actually redo it for free if I asked, and purple or blue shampoo for caramel tones? Don't want to go back in all accusatory if this is just me not looking after it properly.