Poor service

Hi I got a logik blender that jus gave in its under 3yr guarantee I porb hav it now 2yrs I called game Kenilworth and told them I moved and lost slip and I hav no idea which date I bought the blender the lady advise they can't do anything bout it I Ned the slip so what do I do with it now must I theow a almst 400 blender in the bin cause I dnt hav a slip