Feeling ******

Hi, my sisters car had a problem and she took it to Bosch Kempton Park, they fixed it in November 2019 and it was collected because they said it was fixed and my sister paid them around R10 000, on the 25 of December 2019, the car broke down with the same problem and now Bosch is saying they wont fix it again because they dont have a guarantee. Please help because she feels ******