Question for NOKIA CUSTOMER CARE CENTRE

My wife got me the Nokia Asha 205 Chat Edition.It soon started to lose names on whatsapp,could not download images sent to me and battery would last about 8hrs. I was told by nokia shop it was software which they sorted out, but was told that I would be back as the software does give problems.well it now does not download pictures/images once again. This phone is still under warranty.What happen when warranty expires? Is this faulty software?