Corbeil Store at Innes Rd in Ottawa

I bought 3 pieces of appliances about 5 years ago at a Corbeil store at Innes Rd in Ottawa, at same time, also I bought 50-month extended warranty for all the 3 appliances. I was told that I would get back 50% of the premium paid for in-store gift certificate if I don't have any claims.

Last week, I did receive my gift certificates. However, the store gave me three certificates and told me I have to use the 3 certificates separately!!!

I was shocked because: first, why did they give 3 certificates? I bought the warranty for 3 appliances in one transaction, and I should receive one certificate which covers 50% of all premiums paid.

Second, why cannot I use the 3 certificates altogether? I asked the store to show me any document or condiction indicating I have to use certificates separately. They cann't provide anything or documents. Also, when I bought the warranty 5 years ago, no one told me about certificates having to be used separately.