Consumer Redressal

I have been using Tata docomo Network under the scheme of Rs 349- where the benefits i can avail is 1 Gb internet, 1000 mins calling, 100 local and national sms. The due date of the bill was 27th May and i have paid my bill duly before the time. In the next month i was asked to pay Rs 959 or else my outgoing services will be stopped. My questions are- 1. If i am paying before the fine date on what basis my credit is utilised. 2.Why am i being not informed by the company if any extra usage has been done. They asked me to pay Rs 959 on 22nd of June and when i asked the bill , they refused to give.How can you charge a customer without providing a bill? 3. On 22nd of June they were asking for Rs 959 and on 27th of June they are asking for RS 1890.How is that possible. There are a lot of complains which will not fit in the given word limit. I have been duped by Tata Docomo. The consumer court is my last resort. Kindly help