5 year warranty?

2016 I purchased a defy fridge at your store in N1 city. At the moment, the fridge switches on but does make the food inside cold. It has a 5 year warranty. I've unfortunately lost my receipt since I recently moved and must've misplaced it then but I visited the store and was told they should have my details on their system but they dont. No explanation as to what happened to the database. I need help with this please. I paid alot of money to just be told that my name cant be seen after paying for the fridge and delivery. Please assist.