I'm glad you'd do it again. It's better to try than to not do anything at all. Your grandparent's reasons for not wanting her to get help are for the wrong reasons; they don't want to be shamed. If they really cared for her well being and not their image, they'd be doing everything in their power to help her.
I agree. You did the right thing. People often don't want to admit there's a problem because they don't want to know that they have failed. It's sad but it's true and you did the right thing by calling. Not wanting to do an intervention is enabling her and they're wrong for alienating you for trying to get her help. However, trying to get someone help and them actually accepting it are two very different things. I hope things get better though.
I probably would have done the same if I were you, honestly like it's just because you care. The fact that they're in denial about her addiction is pretty sad, if they truly care they should stop denying it and have an intervention or at least try to help somehow. Bailing her out all the time is just enabling her more. It's pretty sad, and I'm sorry that your family has to go through that!
Better to fix something than let it sit and stay broken.