Dunlop admit their fault but we must pay extra to fix the problem

In December we bought two Dunlop tyres and after a day or two we noticed bubbles on both tyres. We took it back to the dealer where we bought it and they recommended we take it to the Dunlop branch in Cape Town where they will check it. Got there we had to wait 4 hours before someone attended to our problem! They told us they had numerous issues with that type of tyre. They replaced it and after few days there were bubbles again. My husband phoned them to make an appointment but no luck getting through on their line. He drove to town spoke to them and they suggested we rather take another tyre BUT IT WILL COST US EXTRA! Firstly, Dunlop admitted they had issues with the tyres we bought and they still put the same brand on my car! Secondly, this is obviously a manufacturing defect and Dunlop wants us to pay extra to get a better tyre!! It is your fault Dunlop so replace my tyres without charging me extra to fix YOUR problem.