Australian supermarket giant Coles is investigating concerns about gift cards purchased in one of its stores, after a customer's social media video about "fraudulent" Apple vouchers went viral.Melbourne-based illustrator Georgia Perry posted to Instagram last night that she had bought four Apple gift cards worth $500 each from Coles in the inner-west suburb of Yarraville.When she tried to use the gift cards online, she found the redemption codes had been scratched out."They're all f****** fraudulent," she said in her social media video."No redemption code, but just, like, weird scratching and, like, glue where the code should be."Four out of four have the same thing."Warning: this video contains coarse language.Ms Perry raised a complaint with the ASX-listed company, but told ABC News that Coles's initial customer response was "very lacklustre and uninterested and unaffected".Ms Perry said she was refused a refund by store staff, with the company's head office later offering her one today after she made direct complaints to Coles and went public with the case.In a statement, a spokesperson for Coles said the company was "working closely with our supplier as part of our investigation into the gift cards involved" It had the same issues, as did the final two gift cards.Ms Perry said she took the gift cards back to Coles but that the staff "could not care less" and said there was "nothing they could do, apparently because gift cards are a third-party product".Ms Perry also raised a complaint with Apple