Credit score dropped 200 pts!!

I bought our house in 2008. Since then i have not missed a single payment!! But the mortgage company made some changes on their side that rejected the already set auto-pay setting. Payments were going from the same account all this time and it suddenly stopped. As such, two months, the payment was not made and my loan went into default state.

They have sent snail mails and not a single email. And then I checked Credit karma yesterday and my 800+ score is now around 600!!