Appointments are not 100% reliable. Saigon is money first, so appointments mean nothing. If you do catch DD, then you can ask for her phone number.
Fyi: she sees many ppl so your text may not come thru to her successfully. I use a codename when I text her so she know exactly who I am. For Her regulars, she does try to keep appointments 80% of the time. Meaning 20% of the time she won’t keep her promise to see you.