Tamilnadu Electricity Board — general query

Dear sir,
Location : tamilnadu, chennai, kodambakkam, pincode - 600 094.
I am planning to purchase a 2nd hand flat and finalized all legal formalities. I observed that there was un-authorized flat built by builder and eb connection also provided to that un-authorized flat. As per cmda approved plan, this flat is not approved. What is the procedure to remove this connection? Does it affect the existing approved flats? Pls clarify.
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