Ridiculous roaming data charge

Has anyone gone to court with a mobile phone provider?
I was travelling to the UAE and I found to my surprise a ridiculous bill of over $12k for allegedly using roaming data though I have never enable my roaming data and always used free WIFI. I have been through all different channels in this dispute against the service provider and this has been carrying on for nearly 6 months now and I won't give up to fight them. Although they offered me some huge discount to the condition I have to renew my contract but I haven't agreed because it's not enough. I have been over 5 years customer with this provider and I have never used data roaming as it is a ripped off.
Would like to hear any advice if someone has been in a similar situation?

Do you have an iPhone? I don't know if this is relevant to you (or if it really can be the cause of surprisingly large bills - Google it for more info) but the 'Wi-Fi Assist" function is switched On as a default setting in iOS 9 and it 'automatically uses mobile data when wi-if connectivity is poor'. Go to Settings - Mobile Data - scroll to the very bottom and switch the button to Off.

This is a very typical unscrupulous sales tactic in Hong Kong used to get people to renew their contracts. I had a similar experience when I switched on roaming to call an Uber in China and got charged HKD2,700 by 3 for a few mb of data. I called to dispute and settled on rolling into a new contract for 18 months whereby the 2,700 charge was written off by 3.