Ah ha - this is a clue. Dunlop used to manufacture a run-flat tyre called Denovo, which was a good tyre except it wore out rapidly, and hence was not very popular. They refined the technology to slowly improve the mileage you could get out of it, but in the end it didn't sell well enough and was cut.

Quite honestly: tyres won't be covered by any warranty. A mechanical fault that caused it, will. So I suspect that she is going to end up out of pocket on this one whatever you do.

I would suspect: traction control system turned on all the time, or tyre pressures that are far too high.