FNB Home Loans - Deceased Estate

My mother and father divorced in 2008, part of the divorce agreement was that the house be transferred to my mother (including the balance of the loan) and out of the One Account. This was never actioned and resulted in my father taking out additional loans against the "original mortgage". Subsequently my father passed away in 2011 and the home loan including the house was never transferred off his name and is now in an estate. After paying the house for nearly 16 years my mother finds out that she owes nearly exactly the same balance as what was originally app**** for. We have been requesting a breakdown of how this is possible for more than 8 years but FNB do not want to assist as the house is in a deceased estate. Today she received a letter stating that FNB wants to repossess her house and she must appear in the high court. The FNB call centre is a disgrace as calls are constantly being dropped or cancelled.