That's what collection agencies do. Don't blame them. The issue is that some piece of perhaps flawed information triggered the calls. Collection agencies use whatever they have as resources to make the collection. For example, if a doctor fails to pay his student debt, the collection agency can cause him to lose his license to practice medicine. More than likely the bank got it right, and they were doing what they would do with anyone else who defaults on a loan.
I don't see anything sacrosanct about military people and their mortgages. If they can't pay, they can't pay. What's the bank supposed to do? Give them the house? Deployed or not, the contract says that payments are due monthly, and on time.