Achievement 'All ears' help

I have been working on the achievement 'All Ears'. In Act 9, I accidentally talked to the NPC in the wrong order, which locked me out of the dialogue option and I couldn't do anything about it. Is there anything I can do as this achievement has to be done in one run on one character, which took me upwards of 20 hours.

There's nothing you can do, except start over with a new character and take care, maybe follow a guide (if you didn't already) or consult the wiki.
HF & GL