Very unfortunate and frustrating situation. However, I have to support the airline. For me the onus lay on grandma to contact you - which is in fact what she eventually did, so, no problem. To expect an airline to give confidential information to an "unknown" person over the phone was, to say the least, a little naive. Hopefully you have now learned from the experience and will make an appropriate back-up plan in the future. This isn't a rant at you, simply a point of view.