How do I fix my hacked galaxy S5?

[AC Question]

Yesterday my phone got a bunch gobbledy gook texts from "3333". I didn't think much of it but now my friends say I'm emailing them spam. Of course I have changed my email passwords, but I didn't get any bounce backs. So I don't believe it's an email hack, but rather my S5 that is hacked. It doesn't turn off and on by itself or anything. But the texts from 3333 and the email (I am logged into my provider's email app) . My mom heard a couple weird beeps when I was talking to her on my cell. I didn't notice them.

Anyhow, How do I fix this? Factory reset? Please help me if you can and thanks for your time

 

[GreyLike]

I am not sure but still I would do a factory reset. Follow the link -
http://www.digitaltrends.com/mobile/factory-reset-galaxy-s5/

 

[Rukbat]

Install a good antivirus (I use Avast). Let it start scanning everything before you go to sleep. It takes a long time (it may be done by the time you wake up.)

 

[Doug Loveridge]

I am having the same issue. Getting text from 2300 right after I text someone. Texting has greatly slowed down. People saying they are hearing strange things when they talk to me that they have never heard before when speaking to me on the phone. What did you do to fix it? Thanks