pieman's branded products reported as ma baker

I went into Spar Yellowwoodpark this morning equipped with Piemans vouchers intending to redeem them and after choosing my four pies as i have 4 vouchers I proceeded to get authorisation from the floor manager to utilise said vouchers. The floor manager on duty informed me that they would not be able to honour the supplier vouchers as the store uses Ma Baker pies not Piemans. I then showed her the sealed pie package indication on the pricing label that clearly reflects that it is indeed a Piemans product and she acknowledged the label however stipulated it is indeed a Ma Baker pie. Hence they could not honour the vouchers. I then went to the pie counter verified the trays are indeed Piemans trays holding the pies in and the actual pie warmer branded as Piemans. Nonetheless i paid for the pies x 4 in full and I have pictures available of the pie trays, labelled pricing and receipt. Kindly address and give feedback as I am very disappointed at the service and the idea that a major retail outlet claims to be using other branding on products they insist are in fact another product knowingly incorrectly marketed.