i dont think you got the right not to change. that meter is belong to TNB. They will come with lawyer letter/police if you insist not letting them to change. Property is yours but meter is belong to them.

If you modified the meter and found out by TNB, they will come and take your meter away and give you a highest assumption monthly usage * how many years you been stealing from them + 1 summon from lawyer. You have to pay the amount charges before you can get back a new meter or electricity.
Moreover, you might have to give monthly kopi fee's to the guy who came to your house taking your monthly usage from time to time.

either you didnt read the whole things or the post have been editted. TNB is not charging rm500 for new meter. Its "someone" else for some "job" to be done.