The People's Operator has a US based customer service team. They are positioned as a carrier who is socially conscious and they will donate 10% of your monthly bill to a charity of your choice. You don't need to do anything, TPO will take care of it all for you.
Seashells contain calcium carbonate. The calcium carbonate reacts with the acid in the vinegar and causes carbon dioxide bubbles to form. Even though the acid in vinegar is weak it can, over a period of time, dissolve shells.
Most calcium carbonate deposits are made up of the skeletal remains of marine plants and animals that have fallen to sediment on the bottom of shallow seas after their death. If the conditions are right, these sediments can build up over geological time to form extremely thick layers.