Calcutta Telephones — Ghost use of my telephone

Sir,
On Last seven days my telephone no [protected] has been found complete dead off and on.When it becomes dead, for testing, I have tried to call from my mobile and on the screen of mobile it is seen that the said telephone no is busy.I think that there is something wrong and some conspiracy behind it.
I apprehend that my telephone bill may increase by the unauthorized ghost call by the miscreants tapping my telephone line.
I am requesting the higher authority of calcutta telephones to enquare the matter and help me to stop the activities of the miscreants.
Thanking You,
Yours faithfully,
Asisbaran Bandyopadhyay.