Regent Road Store in Sea Point Wont Allow You To Redeem Any Vouchers!

Been playing Cell C Rewards. Managed to get a Bootlegger voucher from the Perks. Went to the Regent Road store in Sea Point, and was told by the manager it cannot be redeemed in his shop and I need to go to a 'large' Bootlegger. This is despite the fact that the voucher specifically says 'At Any Store' ! My goodness, it was only a R20 voucher !!!!