Taking action would mean complaining to the school and I'm not doing that because I am sympathetic to the strain teachers are under.
Why would it have to be a complaint can't you express concern about your DC without it being a complaint - it may be their interpretation of what was said rather than what was said but even then it's impact on your DC is apparently concerning and most schools surely would want to be aware. It also gives the school/staff a chance to adjust their language and reassure and re-motivate your DC.
Plus it then gives chance to raise other concerns - like the support being offered - and what need to be done to access additional support in exams.
I'd also be wanting to explore Dyscalculia for your DD and getting school views on that - at least to start with.
I'm not trying to be patronising - but have your tried on-line maths sites for your DD - just in case it's not? It helps my DC having a machine help them, to replay explanations again and again and to go over daily tll concepts till they sink in. I'm dyslexic and there was a time I was so fed up with harping on about my spelling I couldn't bare corrections or helpful advice - spell checkers on word processor were a god send there - no judgement. It was a similar pattern with DS - plus it takes along tome for concepts to go in.
Sometime it's not the first or second time things go in but 31 or 51 - so having something on-line that doesn't get impatient with constant explanations.
www.khanacademy.org This one is free - so all it would take up is time.
I respect teachers and know most work really hard - but when it comes to my DC I'm not going to let that stop me fighting my DC corners - I'll be polite and I don't always what I think is needed - but raising concerns everyone should be professional enough to deal with that.
I would also have though sitting down and working our their options career wise would help point out that even if teachers were saying this ( and by secondary surely they must know teachers aren't always right ) that they know it's not true for them as they'd have a plan.