There are mechanics everywhere in Vietnam, and they are cheap. The word to type is vá vỏ and the rate is usually around 50k. The customer is responsible for paying for this.
If you really are stuck, you can call us and we will rescue you for our standard callout fee of 150,000vnd.
If you rent a Vinfast and you get a puncture on the rear tire, let us know to guide you throuhg the soution.