Very bad service. Last Dec/22, we booked through my cellphone going from Vienna airport to Bratislava. At the exit followed Flixbus signs leading to Platform 3. No bus on this platform for more than 30 minutes. The customer service number listed at the platform did not attend our insistent calls. Asked other Flixbus drivers passing by who told us to go to platform 5. At the end the right bus left from another platform, so we missed it. We had to wait for another bus and pay for another trip directly to the driver. Answering almost a month later, Flixbus service did not want to reimburse the missed trip. So, my advice is to take a taxi/Uber or another bus company, as you end up paying less and have a better service than Flixbus.