Bad customer service at kfc by the manager

Yesterday i received horrible services from kfc sontonga in Katlehong, when i was supposed to use my voucher number. I found the cashier by the name of Abram ..thank you Abram with ur job well done....Abram referred me to her manager by the name of Bella..who ignored me .I have waited from 16:45 till 17:20 without any respond or answer. Whereas i have been referred by Sam Ntuli manager store to have access or use of my voucher becouse of network problem. Bella send o e of her staff member without name tack to me, explaining that vouchers couse shortage to their cashier.......were do i fit in if there's such a problem and what took her so long to attend me or am i not adding sales by using a voucher