Docomo unfair balance deduction and very slow 2g internet speed

Dear sir/Madam, my name is tapash bhoumik. 2weeks ago I had purchased a tata docomo prepay gsm sim card. Everyday it was deducting re.1 from my mobile balance for no reason. After complaining, they said it won't happen again, but the very next day they started unfair deduction of my mobile balance once again. Now they have stopped the deduction of mobile balance but not refunded the money(rs. 50)my lost mobile balance has now amounted to rs. 50. Also, they are providing very slow internet speed on 2g and I am getting 'connection failed' while trying to connect to the internet. Please helpe get back my lost amount, I.E., Rs. 50 and also do something for the internet problems. Thank you.