Dissapointed, unhappy

I purchased a base and mattress from the mattress company in ruining featherbrook shopping centre on the 22 June and paid cash. The sales man was friendly and helpful until my mattress was was delivered and was too high. The delivery guy from the store advised that I go to the store immediately to share my concerns so they can do the exchange for me of which I did and that's when everything changed. I was found at fault for not knowing the mattress would be too when it gets to myhouse. Even though they don't have it displayed in a way a walk in customer can see the height of what they buying. I. Now being told it will cost me R1850 to do an exchange even though initially this was not shared with me when I purchased. Im highly dissapointed as this is a new store in my area that I was supporting and I'm not willing to pay an additional R2000 for something I didn't and can't use and for being seen as a problem for raising my concerns, this is a serious TCF implication and I will take this matter further if I'm not treated fairly abd would rather cancel everything