whirlpool one of the leading mfrDear Sir/Madam

I have a Whirlpool AC & I'm using it from last 3 years.
My A/C is under AMC & now My A/C is not cooling properly & I logged the call with call center. Engineer visited & said that gas has leaked & he took my A/C to his service center to fill the gass without any charges as my a/c is under AMC.
Now I received the call from service centre people are saying that the cooling coils is damaged which need replacement and asking Rs 6000/- for the replacement & it's not under AMC.
they are just blackmailing after taking my A/C in service center, Intially these people has told me that there is only gas need to be filled & now they are just harssing me as my A/C was in perfect condition & according to me this cooling coil is damaged by them only.