They won't give me my car back!

My car started making noises as if CVs had gone. Took it to Kempster. They said it was a suspension creek, was covered under warranty and i must book it in. Did that. Got the car back 3 days later - same problem. Took it in. Now they did checks, give a list of problems. Didn't tell me I had to pay. Went ahead and ran checks that cost me R650+VAT. Now they don't want to give my car back. I never gave any permission to do anything. Why wasn't I contacted at every step and made aware of what was happening? They won't take my calls. Won't reply to all my emails. They told me they close at 5.30 today but won't reply to me to get my car. The receptionist says no managers are there to speak to me. Please help. These are ***** people with no sense of customer service. They didn't fix the problem the first time they took my car. Why weren't all these problems picked up initially? Coz they are *****! Kempster has given me the runaround since day one. Please help me get my car back!