I took my vehicle to them it had a gearbox problem on the 5th of December 2024 it’s been 8 months now they charged me R56 000

I took my vehicle to them it had a gearbox problem on the 5th of December 2024 it’s been 8 months now they charged me R56 000.00 for a megatronic which is too much.I paid a deposit of R26000.00 but till today my car has not been fixed they duck and diving telling me stories.I fed up now need my car fixed or else they must give me my car and my deposit please assist me.