Reliance Trends — balance amount in reliance one card no. [protected]

Address:

Thane, Maharashtra

I had returned one dress and the amount for that was credited in the card(Rs 890) in reliance trend showroom at Korum mall, Thane. They are now saying that the amount is forfeited as the time period of 03 months has expired. How can you do such thing as the amount does not belong to you or given by you. How can you fix a expiry period for that? I want it to be immediately credited in the card so that I can use it.