We need to agree to disagree here Dan. I am not assuming anything. I read the OP correctly.
IF I read the following: "Repair man said he could take these two in, and for "X" amount of $$$, he would return them in "X" amount of time, in "like new" condition. And at that point grandma said: Naaah, just give me the new one, I'm ready for it." I would say: "Bravo! Congrats on the purchase of an awesome vacuum."
Since repair man said: "There is nothing I can do with these, and I happen to have a brand new Avalir in the van", I concluded (not "assumed") that he was lying, because I KNOW that the old ones CAN be fixed (and most likely WILL be), by the "friendly repair man" or someone else.
That's all. I know that YOU know (you are not "Kirbyloverdan" for nothing!) that ANY Kirby CAN be fixed, and that the parts for ANY repair are about 1/100 of the purchase price of the new. If grandma has a lot of money, and needs to have "the latest and the greatest" out there (I think not, because she kept Heritage for appx. 30 years, and G4 for appx. 20 years), more power to her, and no harm done.
I read the OP as another successful coercing tactic, to force a less knowledgeable individual into purchasing something he/she doesn't need ("wanting", and "needing" are two different things as we all know!).
If someone calls for Kirby repair at home, and ends up giving away TWO Kirbys for a new one (plus untold number of "Benjamins"!), because the old ones "can not" be fixed, that certain someone is being straight out lied to, regardless of what anyone says.
Water under the bridge, I guess. Grandma is happy with her new machine, and we should all be happy for her, I agree on that. And knowing what YOU know, I'm sure you can agree that this lady was lied to by the "repair man".