Game stores doesn't honor their promises!!!

I went to Game Canal Walk with my broken microwave, I didn't realize I didn't have my till slip but instead I had thee extended warranty slip as i bought 3extra years atop the 2 that comes standard. I was refused assistance as they said they needed the slip, which I understood, however they told me they could request a slip from head office which should take a week. This was over 2months ago. I had to call back multiple times, given either excuses or a runaround. I finally reached a manager who called back who promised to follow up. Nothing happened after that. Now I'm stuck with a microwave with 5years of warranty that broke in year one, with a warranty slip but no help from the store. All the particulars of the sale is confirmed and can be verified with the help of the warranty slip, yet they feel it's good customer services to behave this way. I used to hold Game in the highest regard for their customer service and would always recommend them for this, however it seems poor standards is the standard across the board.