ycbm
Overwhelmed
This type of case has been on TV many times - to claim a refund etc from a private seller it MUST be in writing
I could legally sell a car and say wonderful things about it verbally but if not in writing it just 'puffing' and has no legal bearing
Horses may be covered differently as they are animals - I do not know the laws on that
Well in this case it was in the advert. But in any case whatever you've seen on telly, you aren't right. A verbal contract has equal weight to a written one, it's just more difficult to prove. If the OP has a witness that she was told the brakes were working, even if it wasn't in the advert, she still has a right to some money back. Getting it may be a different issue, but she has the right.
That is provided, of course, that working brakes does not include brakes that are just about working but might fail any time and will fail in an emergency stop.