Why is my Galaxy S3 having trouble with every type of connection?

[AC Question]

My wife and I both have Samsung Galaxy S3's through Boost Mobile. Recently her phone started taking forever to send/receive text messages (sent texts will be pending for hours before finally being sent, incoming texts might take up to a few days to be received). When calling her phone, half the time it will go straight to voicemail and won't ring on her end. Sometimes she can make and receive calls. 3G internet is sketchy as well. I've compared all her settings with the settings on my identical phone, and nothing seems out of place. Her bill has been paid and she's nowhere near her data limit. This has been going on for about two weeks now. I tried connecting her phone both to Kies and Smart Switch on my desktop computer, and it says it's connecting to the device but never actually connects. The phone acknowledges the fact that it has been connected to a USB cord. In My Computer her phone isn't listed but the computer begins to try to install a driver for the device. The installation initialization bar doesn't move. To rule out the possibility of a faulty USB port/wire/driver/etc., I plugged in my own phone instead. Within seconds, my phone was listed on the computer, connected to Kies/Smart Switch, and there was no need to install a driver. I just turned on her phone in download mode and reconnected it to the computer hoping that it would successfully install the driver, but it's still not working. Has anybody had any similar issues and found a solution? Thank you in advance!

 

[B. Diddy]

Welcome to Android Central! When you connect her phone to the computer via USB, do you see a USB notification in the status bar? If so, swipe down and tap it, and make sure MTP is selected.