My friend is in the middle of getting a divorce and has found out his mortgage has change without his consent?

He has been out of the property which is both a business premises with residential premises above. He has been out of his home and business for the last 10 months. He is in the middle of a divorse and has just found out that the mortgage on the property has been changed from a repayment mortgage to a interest only mortgage. Can this be done without his consent? The mortgage is in both his and his ex-wifes names. He has also found out that his ex-wife has not paid the mortgage for the last 5 months