They actually have all the right to sue you.
But what they are actually doing is that they are denying of any further services from "mobitel" ...
But the worst effect would be that your name will be black marked in the CRIB which in turn will effect you very badly in the future if you want to take a loan. ie: housing loan, car loan etc etc.
They will refer to this list and mark you down as a defaulter and deny your applications to such financial loans. The long you wait, the bigger or rather harder it would be to get your name cleaned up.
So., i suggest two things !
1. Wait for three years without no interaction with Mobitel. Not a single call., not a single mail.. basically nothing written or verbal with them. Because after 3 years usually all financial liabilities become null and void unless otherwise any other undertaken is taken or given. But you will be denied of other services or loans during this time
2. Pay the fucking 2000 bux and get your name off the list... "TAKE" a letter from them (mobitel) that they will remove your name off the list !
hope it helps... if you need anymore clarifications.. please do jot down here and I will reply