I take it you rent a leasehold property (flat?) on a tenancy agreement via an agent rather than the owners of the actual flat lease.
If there is nothing you have signed up to for liability for any such charges I would get the agents to doublecheck the origins of and terms of any such obligation and validy of any charge eg in the actual lease of the property itself (not the tenancy agreement) and, if it is a valid charge, who is properly liable eg the owner of the leasehold flat.
It might be that your tenancy agreement refers to abiding by the terms of the flat lease where they may be obligations and penalties. Have you got it to check?
If there is something you have signed up to otherwise agreed to then this should be able to be produced.
Who is the fine from? Is it a management company of the building?