bad service and no feedback

Early Jan we purchased items on Eat in under R150 - but did not get discounted price. Phoned store and was told they would reimburse next time I went there (approx. 40km away). When I went back the \Manager"told me we did not get the discounted price because we did not purchase all items - he tried to show this to me on the poster - clearly it does not state this! He gave me a R50 voucher (which barely covers the overcharged amounts) - BUT his attitude and patronising manner were unacceptable - and he continued to argue a point on which he was clearly wrong. I have subsequently called customer services on 3 occasions"