But one get one free

We had a verry bad experience at this store. There was handbags for sale, the price tag on it R200 and a sign that said buy one get one free. But when we got to the till to pay they told us sorry we had to pay R300 for the bags because it was actually buy one for R200 or 2 for R300. My point was just that if they mark the bags R200 and have a sign on them staiting buy one get one free should you not pay R200 for both bags then? When we told them that that's the way it's marked we were told sorry but we can't get the bags for R200 as stated we had to pay R300.