Paid but no repairs

Mechanic misdiagnosed the issue in my car. They told me to replace the door lock then my boot will be able to be repaired. I then paid R5200 for the repairs for the door lock but the boot is still broken. They now give me another quotation for R16 400 for the boot and want me to sign that they did the repairs and still adding labour again on the quote. When I refuse to sign because I brought the car because I wanted to fixed my boot and it not fixed they refused to give me my car. I then asked my friend to pick me up because they refused to give me my car, I am a woman what can I do to man who are taking advantage that I won't do nothing. I then went back to try and get my car back because I need it they then forced me to sign before I took it. I so hurt and disappointed after buying 4 cars at Kia, this is how they treat me. To make it worse I asked for my 2 car keys that I gave them when I brought in the car because I knew they had to reset the keys, they told I bought in 1 keys, even general workers and all kia employees who were there attested that I brought 1 key, after a long adument they one of they find the key and they acted as though nothing happent. My heart is saw because I feel they all ganged up against me, I regret ever entering that dealership, KIA WELKOM.😭. I walked out there in tears.