Hey Savit, thought I would add my 2 cents in and share my costa experience ive had over the last week.
Ive had the Costa Blackfin with grey 580 glass lens for about 3 years. Last week after being out in the boat I grabbed my fishing bag out of the boat along with some other bits and pieces and my costas which were in their case fell out of my bag with out me knowing. It was dark and I accidently trod on the case and smashed one of the lenses to pieces. Over the last week or so I have been deciding weather to repair them or buy a new set. I spoke to the guys at Repala (Costa Australia) and decided to get the lense replaced. They don't do single lenses so I agreed to get 2 new lenses but I changed from the Grey to the green mirror. Part of the rubber on the arm had deteriorated and they said they will replace the rubber under warranty and i'll just have to pay for the replacement lenses.
Yesterday I received a call from them saying they don't do the same colour frame as what I have but they will put the new lenses into a brand new frame under warranty! So I decided on the realrtree camo frame and just got them delivered to me at work this morning. So in the end it cost me about $160 for a full new pair of glasses as opposed to the $370 - $400 cost to buy new ones.
Absolutely stoked with their after sales service and the outcome. As someone mentioned earlier their customer service and warranty policy is second to none. Cant recommend them enough. Heres a pic of my new glasses but obviously I'm yet to try the new green mirror lenses... A very happy customer...