Cell Phone Bill

I had a postpaid connection with Vodafone in Hyderabad, and I had been using their services for several months and paying my bill on time. I was then transferred to Mumbai, and I within 2 days of arriving there, applied for a pre-paid sim and pre-paid 3G dongle for internet, giving whatever documents they asked for. A company letter from HR was my address proof, which is enough in most cases. The SIM was not activated after 1 week, inspite of my follow up calls to vodafone in Mumbai. I applied for another one soon after in a Vodafone gallery (the first was in a Univercell Sync) and made it all official, giving them copies of my passport and PAN card and a HR letter. This was also not activated. I followed up weekly thrice, I had a busy schedule which also requires me to be on my phone constantly. I called Customer Care Vodafone several times regarding this, and it was not honored. During this time I was forced to use my Hyderabad SIM which racked up a huge roaming and internet bill. I refused to pay this bill purely on principle. I pay for a service, and the service should be what I paid for. I have received several calls, and on the alternate number of my Vodafone account which is my mom's number. I was forced to use a third party app to block all such calls which were 10 times a day. I also have received 3 emails from [deleted], and 1 legal (barely) from a local small time advocate, telling me to pay the bill or legal action in court will be taken against me. If it does end up in court, will it end up costing me even more, even if I win? If I lose, of course I'll be court ordered to pay the fees, and legal charges to my lawyer. Should I drag this out even more?