You can't turn around an entire country so used to corruption in daily life overnight. Start by funding anti-corruption media campaign to highlight how corruption effects the lives of real people. Many in Vietnam are uneducated about how taking small bribes and gifts can adversely affect an already bad economic situation. Highlight it through pictures, stories and examples of just how costly a human toll it inflicts on society. People might not care about a government employee being paid to pick on contractor over another, but they might care how well a bridge is built and whether or not it's of good quality or not; as their lives depends on it standing. Give them a picture of what a normal society with little corruption looks like (I.E. Singapore). There's ample ways, the question you should really be asking is, is the will there to end the practice? That question is one the Vietnamese people themselves will have to answer.