Bharat Sanchar Nigam [BSNL] — excess billing in broadband free trial 5gb data per day scheme

Sir,
I have a landline connection of bsnl[protected]. As per the information regarding broadband free trial for one month promotion scheme of 5gb data per day in the calcutta bsnl website, installation of broadband is free and no security deposit is required. I have taken free trial scheme on 25th october, 2019. But in my telephone bill for the month of november, 2019 the install charge of rs.250 and security deposit of rs 500 has been added with my landline telephone bill.
It is requested to look into the matter and waive these extra charges from my bill.