You don't know what you know till you get it in writing

DH had to deal with Mom's bank again.
Earlier this week DH emailed his contact at the bank regarding some other problem. Today he got a call from the bank from another person, not his contact person. This person, last week, alerted us to a liability we were completely unaware of, let's call her C3. We'd (really DH) been working with our #1 contact (C1) and a secondary contact (C2) for the past 2 months. Lots of back and forth calls and more recently, back and forth emails.
Well C3 comes out of the blue about a liability that C1 & C2 completely failed to mentioned the existence of in the past 2 months.  When we found out about this liability, DH emailed C1 and later at my insistence, called customer service. Unfortunately, the problem or getting some concrete info was above customer service and their manager's pay grade. C3 calls again wanting DH to do something about the liability to find out C1 and C2 are out of the office for the week. Also C3 claims that DH was informed of the liability last month.
Uh, no.
The problem with the numerous phone calls is and has been whatever information is transmitted about Mom's accounts or whatever is whatever DH happens to scribble down or happens to remember from the conversation. The only thing we know is he got a call or he made a call, the contents of the call are unknown unless the NSA would like to provide us with a copy. There is nothing in writing; nothing in email that alerted us to the existence of the liability. Well nothing until DH decided to write the bank about it this weekend.
SIL (sister in law) left a mess when she decided she was done with the care of Mom. Well the whole plan to care for Mom was a disaster from the start, but that is just my opinion. When Adult Protective Services got involved you have to wonder what went wrong (Mom running away from SIL). However we really don't know what went wrong because we have to go on what people are telling us and the story keeps changing, even from the same people. I'm trying to impress upon DH he needs to get it in writing, whatever anyone is saying, get it in writing, because it can change next week.