Taxi scams are a well known problem in Hanoi. However what is less known is maybe that the concierge at Sofitel Plaza is involved in the scams or at least is collaborating with the scammers. My GF experienced this twice. First. We got a taxi from the Airport but since we only thought there was one Sofitel we were driven to the Sofitel Plaza instead of the Metropole. At arrival the taxi driver suddenly demanded more than double the fee we had agreed on before getting in the cab. I asked the concierge for help but he actually sided with the driver telling me that I had to pay. After getting a manager this was sorted out and the taxi driver left (with the amout we initially agreed on). Second: the day after, my GF got scammed again when she was out shopping and ended up close to the Plaza. Asking the same consigerge for a taxi back to the Metropole he got one for her. However this driver also tried to scam her by driving around in circles for 40 minutes (for a 10 min ride). Beware.