Veteran discount

My husband bought me a phone and signed up to get a Veteran's discount.  He took in his evidence of service to an AT&T store.  Since then, we've received three notices saying he needs to submit proof of his employment or he won't get the discount. He is 75 years old and has been retired since 2002.  He receives only retirement income.  What gives?  The AT&T store employee said not to worry when we got the first notice, as it is only a computer-generated notice, but now that we have received a third notice, saying he has only one day to submit evidence, I'm a bit worried.