Bharat Sanchar Nigam [BSNL] — BSNL WIFI connection issue

Address: 5710201 Madikeri, kodagu, Karnataka

I had got the BSNL WIFI connection on May, they charged me 5000/- for installation and informed me that the first month internet service will be free. In the month of June, I received the bill for both the months May and June the sum of 3267/- When I visited the BSNL office to check on the issue, they informed me that they do not have any relation with the Modem installation team who informed about the free service, and I will be charged for both the months. I did not pay the bill and the internet service was stopped on June. I have received the bill of rupees 5395/- for all the three months again for May, June and July. When I personally visited the BSNL office again I did not get proper explanation and asked me to contact the BSNL customer service for query, when contacted they did not have the proper explanation and they are asking me to visit the BSNL office. I am tossed back and forth without resolution or any kind of help with increasing bill without using the services.
Kindly help