Palmsprings branch not wanting to service us because we were using coupons

Went to buy food using hungry lion coupons from Vodacom that were worth R300, the lady on the till said I can only use ten and then changed her mind and said I can use 5 after that she said they were offline,and she said we must try tomorrow or go to Eyethu mall, a coleuge wearing a diffrent shirt he was busy with ice cream said she must try made wait on the side for 10 minutes and then called us and said she wont take all 15 and she took 10, my question is the coupon money not money? why give us such a service as if we here to beg for food? why does hungry lion partner with Vodacom if not willing to service Vodacom customers? please respond and notify me of a way forward as I stay close to Palmsprings and if I will continue to get this service or if we must stop, we annoying your employees