Vodafone Bill Issue

Hi, I need advice for my Vodafone postpaid bill issue. I had taken 3,500 Roaming pack for Greece, But in a layover to Bahrain, I was connected to a third party network and data leak of around 50 MB happened. Please note I was not informed that I got connected to a different network and about the charges as well. My credit limit is 3,000 but they have charged me around 50,000 for 50 MB data leak which i never requested for Bahrain or Was never informed for the data charges rate in Bahrain. Vodafone discontinued my services in Bahrain itself and I couldn't use my 3,500 Roaming pack for Greece. Infact, My services to the number was barred and I was in emergency situation in a foreign land where there was no incoming, out coming or message facility available on my phone. Now, Vodafone has given my reference to a fake advocate who called me and has given warnings last week. Today, I got an email from Vodafone about Pre litigation case in court. Please help me on how should i respond.