Labour amount for gearbox

I took my car for 45000km Services at Reanult in Roodeport Ontdekkers, I assume or knew that - when you take your car for service, the car will be checked for everything, so I did not tell them any of the minor issues I had. For my surprise after the car was service, I noticed that the hand brick was so soft in a way that when I park my car on a hill I have to put a brick behind the tire so that it does not roll back, and the worse part was that my gears did not have power like before - they were weak. So, I called them, and they told me to bring back the car, they will work on the hand brick. For the gears the technician said he will do something about that, after 1-2hours I then asked the consultant lady what is taking so long because I must go back to work. She then says that -they must take pictures of the gearbox inside and send the pictures to the maintenance people to see if the issue was caused by what. A totally different story from what the technician said to me. The lady then said that I must sign an agreement to allow them to open the gearbox and I must also pay the minimum amount of +-R3600.00 for labour of opening the gearbox, and if they find out that the problem is not normal inside the gearbox, they will want me to buy parts to fix the gearbox. I told her that I don’t have that amount, can they do everything under the plan(Service plan and Maintenance plan), she then say that- that amount for labour must be paid before they can open the gearbox, so I told her to call the technician and then she said he is not around maybe he went out to test another car on the road. I then told her to give me the car key- I must leave because I do not have that money. She then said she will call me. I am still waiting for her call. When I was talking to the technician, he told me that he will work on the gearbox, he did not tell me anything about the money. So, while I was thinking of a plan to raise that money so that my car can be fixed, I then decided to look at my plan (Service plan and Maintenance plan) thoroughly, I am covered for gearbox. I need clarity here please; Do I really have to pay that labour amount of opening the gearbox??? Do I really have to pay any amount if I am covered?? The car is not in good condition after the service at all, it is worse than before, I don’t even think that they have changed the plugs, or filters or whatever, because the sound of the car of “that sound that says I need service” it is still there. The globes and brakes and some were done. When the car is from the service, the driver must feel/hear the improved performance of the car. I need/asking for clarity here please; Do I really have to pay that labour amount of opening the gearbox??? Do I really have to pay any amount if I am covered??