Start menu>Control Panel>Change or Remove Programs. Click on the application and click uninstall.

I would highly suggest not using rice unless it minor water damage and you wrap the phone in paper towel beforehand. Typically rice will get into your ports and it also has a lot of dust in the rice. I would suggest trying to follow along with a breakdown video as far as you dare to go. Then take canned air and spray it. Then leave it out for a day. If you don't want to take it apart, or the above solution doesn't fix it, almost all repair shops fix water damage. Sometimes water can damage to a point of no return; in this case, you can try replacing the motherboard in the phone, but at that point it's probably time to get a new phone.

If you want to charge your battery faster, use an ipad charger. They typically charge at a higher amp. However be careful, some chargers can damage your lightning port and short your battery.

I'd suggest asking for your money back and going to another shop. Sounds like they just don't want to fess up to their mistake. Good luck.