Accessing client responses to automated texts

When a client receives a text reminder for an appointment, and they respond to confirm. That response does not reach the office. When we call the client to confirm the appointment, the client becomes upset. The clients feel that their time is wasted and that they are not being heard. If there is a way to tie the responses to an email account or an outside texting resource (we currently use Textline with the main office number so there is consistency for the client).