Vodafone Prepaid — Being harassed by unknown person

I have two sim card. I am a vodafone customer for last six years. My numbers are : 1) [protected], it remains with me & 2) [protected], it remains with my sister for last 6-7 months. An unknown person from different phone numbers ( mainly from -[protected], [protected], [protected]) is enquiring about some GOPAL DAS who, according to the unknown person has taken some lone and given my vodafone no ([protected]) to there. Under such situation, I am now in an embarrasing & painful condition. Please take necessory steps at an early date in favour of one of your valued customer like me ; otherwise I shall have no other alternative but to surrender my SIM at my nearest VODAFONE SHOP (at nagerbajar, kol-28). Thanking you in anticipation.
Yours Udayan Sengupta
(date of birth -13.09.1959)
MOB NO -[protected]
ADD- 47/15, R.K.Ghose Road, Kol-50