Many mineral buyers are the scum of the Earth, in my opinion. Most of them are not real landmen and don't follow any rules of the AAPL. They have the same ethics as a cheap fly by night used car salesman.
I have been approached by a number of companies wanting to buy some or all of my royalties. I only had extended discussions with one company, Live Oak, in Houston, and found them to be very up and up. Our family chose to not sale any of our royalties, but I'm just trying to say that all of the companies buying minerals or royalties aren't bad.
It saddens me to read about your situation, Jane.
And this points up the importance of using the services of an experienced oil and gas legal firm to negotiate any contracts and offers. The attorney would have caught that decimal interest discrepancy and saved you and your family money, time and anxiety.
Plus, if your royalties are potentially substantial, and/or come from multiple wells, a good forensic CPA who will audit production would be extra protection. They can ensure that the operator pays the decimal interest you are owed and keep the operator's fees/charges in line with your leases.