What happened to you is absolutely not the norm and unacceptable! This is breaking into the phone through the network and this is a real crime. But unfortunately, we cannot make a person responsible for his actions because most likely he did it with a VPN and is generally far away from you, and maybe even in another country. Therefore, you need to be aware when you download something on the Internet and answer some e-mails, or even when you choose your mobile phone operator because some cannot secure your phone data. So I advise you to read this article "telecom revenue assurance" that explains how can you secure your phone from fraud via trustonic platform.
Hi, I am very sorry to hear about your recent experiences on your device, and can understand how frustrating this situation is. If you’re worried about your phone getting hacked, or if you think it may have been hacked already, there are some steps you can take to keep it safe. For example, you should only download apps using the Galaxy Store or Play Store and you shouldn’t click on malicious links in apps, texts, or emails. You can also keep your phone safe by running anti-malware apps and removing apps that are causing issues. Try this guide here in addition to changing your passwords and eyeing transactions: https://www.samsung.com/us/support/troubleshooting/TSG01209886/
Please let me know if this helps.