Voltas — AC defective in less than 2 years

Address:

Kolkata, West Bengal

I had purchased a Voltas 1.5t 5S split AC in the month of May 2013. This summer (April 2015) I noticed that the cooling effect has been drastically reduced. I booked a complaint through Volta's Customer care. The technician checked up and said there is leakage problem and took the outer unit to service centre. The following day, I received an hand written Estimate Quoting Rs.9662/- ( Supply of New Copper Coil Rs.6800/- + Gas Rs.1800/-+ tax ) and requesting to pay 100 % upfront favouring to a company( May be a outsourced service support company). Now, I am really doubtful about the genuineness of the services and quoted rates ?? How can a product of such a trusted brand go wrong in less than two year of time ? Even if, it does why the company is charging huge among ( = app. Rs.10000/- i.e. 25 % of product value) for repairing ? kindly advise me, 1. whether the RATES are genuine ? 2. If not what is the alternate recourse ?