Hello. So sorry to hear another story like this. Iโm sure you have seen from the thread just how many of us have been effected by the same issue. Nottingham Audi are certainly aware of the issue and I did ask them if they would now stop selling Dunlop max tyres to A7 owners and they wouldn't give me a straight answer.
Your tyre splitting IMO has nothing to do with the slight under inflation. You have done the best thing by changing them over to continentals. I have done the same and so far Iโve had no further problems.
As you may have read I did eventually get good service from Audi who replaced one of my tyres at their cost and 3 other tyres which had all split I got changed using my tyre insurance