Was given wrong marchandise and got blamed for it, calle to enquire and got blamed for their incompitences

I recently moved to a new place and bought three beds, a queen and two 3/4 beds( supposedly) and they were delivered. I used old sheets till it was month end then when I brought the sheets for the 3/4 beds they were not the right size. The sheets were way bigger than the beds. I called the day after tot tell them, they said they would revert back to me, which they didn't. Every time I called they would come up with different excuses one being that I actually wanted the single beds instead of the 3/4 beds. I was so furious and felt short changed. I paid for 3/4 beds and they did not want to change them because they said their policy says its too late to change the,. But why should I take responsibility for their unprofessionalism. The likes and lack of customer service was disgusting to say the least. They have turned what was supposed to be a good experience into a despicable scene. I have always been a loyal client to the store.