I am glad for you that your issues seem to being resolved, but did MMC have a view on the cause of failure of the wishbone ?
That type of failure could have had catastrophic consequences had it occurred at higher speed.
Our conversation was about warranty issues, so I have no detail on the cause of failure; but MMC reiterated that this was the only new-style wishbone problem of which it was aware. With both this and the original wishbone support issue reported by Rog G, the problem occurred close to welds (ie where heat had been applied) - maybe that had something to do with it.