Airtel Broadband+landline — wrong bill

Address:

Bangalore, Karnataka

i am Anup Mandal having airtel broadband connection from 11/jul/2011 to till date my account no is [protected] and tel no is [protected].
today (12 dec 2011) I got a legal notice on my name from SHIVA & RAWLEY Advocates asking me to pay the outstanding Rs 3750 within seven day which is towards the account no: [protected] bearing tel no: [protected] which i am not using and have no idea from where my name came from and the address stated in notice is not my address
after receiving this notice i called airtel customer care about this and surprisingly i found for this account (no: [protected]) my mobile number which is [protected] is registered i told him i don't know about this connection and the postal address mentioned in the account detail for this connection is not mine he suggest me to Wright this mail and send it to 121 for further action so i did but not received any positive reply please suggest me what i can do regarding this.