Incorrect plugs supp**** by Midas Ladysmith

I bought a set of 4 spark plugs from Midas Ladysmith for my Vehicle (Peugeot 207 GTI) in October 2022 - the salesman (Godfrey) checked on the system for the plugs and we were supp**** with PLZKBR7B-8G. I had a mechanic install them and, because I was moving house from one place to another, the car was rarely used (I must have put on about 50km) after the new plugs were put in. In January 2023 I started to drive the car more frequently and realized that the car was jerking. I took the car back to the mechanic who diagnosed that 1 of the spark plugs was not working. So I went to the Midas in Ladysmith (in February 23) and asked them to send the plug for testing and I bought another plug to replace this plug. Not too long after this the 2nd, 3rd and 4th plugs stopped working over the next few weeks as I started to use the car. I realized that something was wrong and I bought another plug (4 + 2 =6 plugs altogether) and I took all the 4 plugs back to Midas for testing as I assumed that there was something wrong with the 4 plugs that I initially bought. After a very long wait and constant pressure from my mechanic we were told that the plugs were fine and that something must be wrong with the car. Just out of curiosity I googled the type of plugs that my car uses and I saw that my car takes the PLZKBR7A-G and not the PLZKBR7B-8G. My mechanic has constantly been asking Midas Ladysmith for a full refund for the 6 plugs that they incorrectly supp**** and they refused. Now the salesman (Godfrey) is saying that he supp**** me the plugs based on my sample which clearly is not the case. This is going on for 3 months now and my vehicle has been also standing because I need Midas to take responsibility for supplying me the incorrect plugs and I expect a full refund for the 6 incorrect plugs. This is frustrating as I always buy all my spares from Midas Ladysmith as I have always trusted them.