After ordering a 8GB Sandisk Ultra 11 Compact Flash Card from a 'nameless' online store and received a plain Sandisk Ultra CF Card instead am wondering if I can use it in my new Canon 5d 11?

Have tried to return the card but the store is being difficult about issuing a return no. for a refund/replace and I have a suspicion they are having difficulties so I am probably stuck with the card hence my question.