Hi , my radiator failed, water mixed with cvt gearbox,  flushed it , but now seems lower gears starting to slip, especially when driven about 20 km . They say a replacement assembly with labour wil cost 72 thousand rands.  What to do now ? Vehicle such good condition.  

maybe another flush out of the fluid as it could be still contaminated.
Refill with the correct fluid and see if that changes anything