Privacy of WhatsApp messages
No, he shouldn't be able to, as far as I know WhatsApp encrypts the calls and messages that are sent through your carrier's data service. 

Anyways usually if you ask a phone carrier to produce a call and message log for a line they'll show you the calls and messages you've made and received through actual SMS messaging and cellular calls. Since WhatsApp passes the encrypted data from your device as data calls there would be no way for T-Mobile to show the contents or recipients of the calls or messages.