Can customers see my private data

No. Customers can only see the data in your profile that are  marked with an asterisk. Your private data can only be seen by the management team and will never be shared. If a customer ever asks you for personal or contact information, such as your mobile phone number for WhatsApp, please politely decline for your own protection. Customers have multiple communication channels (our app, email and Skype) where they can reach you.

Here’s a little wording help:

Hello x, thank you for your inquiry. Unfortunately, on the part of my-vpa, it is not permitted that I provide you with my private cell phone number. But you are welcome to contact me via our app, e-mail or Skype. Thank you very much for your understanding.
Many greetings x

Does a customer want to learn more about you and your skills?
Then always refer him to your profile in the app. There you can maintain your work experience and upload skills including work samples. Please never send your CV or work samples directly to a customer!