Bad customer service

I bought 3 items online with 40% discount. I went into clicks Cresta as I wasn't happy with the one item the manager Thoko told me I could exchange the item which I told her was a safeway sandwich maker for the Kambrook at the same discount. They put the item away took my details. Today I returned the item for the one I want I get told I only qualify for a 20% discount cause it's not the same thing. Yet I spoke to the manager the day before. I'm not a happy customer they call the manager she doesn't come to light. Really bad service