Sadly, back to square one!
I didn't get a response from MMF, so I went to the Ombudsman.
Long story short,
a copy of the default letter was sent over to the Ombudsman.
Despite pointing out that we had never received any written correspondence so it appeared odd that this had been sent by post and not email (i.e I don't believe it was sent!), the Ombudsman has accepted it.
MMF apparently changed their systems so cannot provide any copies of letters or emails sent prior to the default notice, so they have provided examples similar to what would have been sent (!!!)
Ombudsman has agreed that they should backdate the default to 2013 when the debt actually defaulted. Mr Lender apparently registered a default but then removed it once they realised they had not sent a default notice.
I've been told we have 2 choices, as a lender does not have to report to credit agencies, keep the default as 2016, or back date to 2013, so when we look at mortgages it looks as though it's been ignored for 4 years.
I guess the second option is the better of 2 evils...
I'm astounded at how slow the Ombudsman are!
And very disappointed that they agree with MMF despite the fact they cannot provide copies of correspondence and do not report to credit agencies.
Apologies - formatting appears off yet again!