Non T-mobile customer

Hello there!

How can I contact t-mobile customer service if I am not t-mobile customer. Moreover I am not in USA.

If I click "message us" button the website requires my t-mobile phone number.

I have not the number. Other numbers are invalid.

For example, Sprint has online chat, where I can contact exactly an agent of Sprint.

Or I can contact the agent by writing to him via private message in Sprint community.

What I should to do to contact T-mobile agent?

Please, do not advise me to make an international call to the service. I know about this method.

I want different methods, such as have mentioned above.

Many thanks to you in advance!

Have a good day!