False advertising

I opened an account and received a voucher to spend R800 and get R150 off. I went to the store in eastrand mall to buy and I was told voucher does not work on sale items so I asked why that was not specified on the voucher? They called David the manager and he said he's busy I must come to him. Which I found very irritating then he came a d told me to calculate if buying sale items on voucher makes business sense. I then asked him to call head office, he said the store does not call for voucher queries I must call them myself and left me in the counter. I am so irritated, I left my goods to the value of R970 and will be closing the account