Is there really no way for U.S. Citizens to get a Bietnam visa in Kunmimg?

We are currently in Kaili and plan to go to make our way into Vietnam through KM. We were told we can get our Vietnamese visa in KM. If we cannot, we will have to make our way back to Shanghai to catch our return flight to Phnom Penh before making our way to Vietnam which is not what we want to do. Please advise.