Vehicle worse after repairs

Its become one problem after another with Durban Central Panelbeaters and Mervyn! I've recently changed my back wheel that was repaired by the panelbeater. Reason was because the inside of my tyre is worn. I've had all my tyres checked and found that it was only that one tyre that was problematic. I have now bought a new tyre and upon changing the tyre they discovered that the tyre had a plug due to a puncture. Note that I have NEVER had a puncture nor repaired any of my tyres. It is quite obvious that DCP has taken my tyre and put on an old damaged tyre on my car. My tyre Contisportcontact 5 is difficult to get. I want my tyre back from them.