I wanted to change my car rental period and wanted to do it quickly. I had to do this through Opodo. The Opodo overseas Customer Service number was not recognized. After many failed attempts to get in touch I phoned the rental company, Sixt, who were tremendous and saved the day. It was a shame that Opodo let me down as the initial booking process was effective and efficient. User's recommendation: If you don’t need Opodo Customer Service then worth a go.