INEFFICIENT SERVICE & MANAGEMENT

I got a Builder's card in August & was told 15% first online purchase. I bought a few things & paid via credit card. I then realized the 15% hadn't come off. I phoned the call centre immediately & the lady said she couldn't cancel the sale or change it but to go to any branch near me & request the difference of over R200. I did that they said I should write to HO which I did & was I formed the offer was over. But confirmed I purchased before the offer was closed. After going backwards & forwards they wanted the number I used to phone the call center to sort out. Now for the last 3+ months nothing. Come on an offer is an offer & done in the ti.e allocation so it needs to be sorted out.