Tata Sky — charged for changing the super lnb

I have tata sky (No hd) (6 years old purchased set - subscriber id-[protected]). I was facing no signal issue for more than 3 days so i raised a complaint with tata sky.

Post analysis, technician told me to replace the lnb as my dish had universal lnb instead of super lnb and this will cost 570 rupees! I discussed with him that if this was the lnb which should have been for set-top box then why did they installed the other type of lnb earlier? Moreover such replacement shouldn't cost as the earlier one was not faulty/damaged. But all discussions went into vain and finally i had to give him the money he was asking. Upon asking about the bill he said I will get it on message. My suspicion got stronger when I called customer care and asked about the bill info and warranty of the lnb . customer care representative said if you have paid the amount to the technician then you will not get the bill details on message. I insisted him to pay the bill online then Why the technician asked for the bill amount?
Since for my set top box it was supposed to be super lnb then why do i need to pay 570 for it. Moreover why did the earlier dish (Complete new connection) was installed with in-compatible lnb. He has installed a lnb of company called 'Sharp' when I searched for the price online I got to know it only costs 240 rs.

Please take actions at the earliest and revert the amount.