Honda Cars India Ltd. — my honda city car at regent honda thane maharashtra

I dr dhiraj mahangade a orthopaedic surgeon at thane have a honda city diseal purchased car in feb 2014... On 27 november i started mr car and driven 4 kms it ceased... Cannot be started.. So called road assistance and got towed at regeant honda service center at thane ghodbunder road thane west... Now at service center i was told that engine has to be opened as water and oil got mixed due to over heating and gasket got cut.. I was shocked how can a honda car just driven 4 kms got over heated... When there r different gallery for oil and water how can it gets mixed??... Secondaly 10 days passed iam not given a estimation or any progress of car... My car is regulary serviced at same center... And is covered in extended warranty... Yesterday i received a call from adviser asking me to give approval for rs 15000.. To only open the engine... Now my car is under extended warranty.. How can i pay 2 lacs for which nis not my fault... How can car get over heated... That too honda brand??? Hence forth would not recomend to any one to buy honda city... Even service center not bothored to give feedback... Proper estimation even 10 days passed by... Kindly plz look into this matter at it is serious matter