Tried to cross into Vietnam today but tuned back for not having documentation that's not actually needed. Thought it could be a $20 problem but it wasn't (and no it wasn't a $50 problem either). Heading to Phnom Penh to try another boarder. Joys of travel (feel like I will be saying that a lot).
Cambodian boarder police were cool though. We smoked cigs and talked shit for 30min while Vietnam checked more fake rules (well what pertain to me)