Fraudulent Outgoing International Calls from U.S.

I just had three phone calls that were charged that were supposedly outgoing Wi-Fi calls made within 10 minutes of each other. All the calls were to the same phone number in Belgium.  I never make international phone calls! I scrolled down through all my outgoing calls from that date in May and nothing was accidentally made on my end. I find this very Suspicious and somehow my phone was either breached or T-Mobile system is breached. However, the charges were only $42.53, T-Mobile customer service was so kind to remove those charges from my bill and turn off any international calling. I don't even know why I would have International Calling on, seeing I never make any calls overseas. Thanks T-Mobile for trusting that I did not make those calls!