There is a 40% shortfall of maths teachers nationally.
Complaining to the school is pointless.
if you want to do something constructive, complain to your MP about the working conditions of teachers. Tens of thousands have walked out it recent years, (I'm one of them) The work load was little short of slavery, 90+ hours a week as standard, several times a week there was no opportunity to go to bed at night, and almost all of it pointless paperwork, record keeping, writing ever changing policies into schemes of work, etc etc etc.
For example, one of the last jobs I was given was to return to a years worth of lesson plans and write into each one exactly how I was promoting equal opportunities for ethnic minorities in the way I intended to teach every single lesson, individually for the next 12 months ( in maths!)
This was BEFORE the topics I was teaching had been allocated, so the lessons I was writing were imaginary anyway.
I could give you dozens such examples.
i am now in and out of schools as freelance or supply, and lookingat the situation from the outside I am horrified and disgusted at the treatment i see teachers endure. last week I deliberately timed one individual on the photocopier.
just under 11 hours. This is not unusual in the slightest.
Anyway, sorry, once I start, I find it hard to stop.
Contact your MP!