I just collected all 54 gnomes and I also got the achivement but I didn't get a phone call.
Nope, the phone is no longer part of the progress and neither is the bomb. You just collect all the gnomes and then head to the sewers. You'll find the entrance to go down to the gnome area just past Rux's store to the left.
Enjoy your rewards! And do continue on to solve the gnome puzzle (either on you own or with a guide) for more treasure.
@ollyduck wrote:
It`s the Snow globes challenge once you got all them pesky golden ones!
I had meant to mention that you would need to enter the gnome puzzle room in order to finish the snow globes.
Once you open the first chests, you will need to find the mushroom switch in the chest room in order to access the final room with the puzzle.
Hey @KnowItAllKingFTW, did you get it all done yet? Happy with your rewards? I remember that when I was at that point in the game, the coins I got allowed me to pretty much finish off collecting the stickers for all remaining regular variants.
