MTNL — unauthorised levy of charges

Address:

do not know

I receive unsolicited messages on my mobile [protected] and when opening the same, the following messages appear:

[protected]
"dear user, thank you for downloading!! You have been charged rs 7 for the download!!"
Message details:
Type: text message
From:[protected]
Sent : march 28, 2019 17.38
Service centre
[protected].

This has happened on earlier occasions also. I do not ask for a download; there is no warning of the charges in the message.

Kindly take necessary action.