Very disappointed

If I was to give it a zero star I would...So I bought a clothing online this Black friday only to find that the size is not appropriate therefore I went in-store to take the right size, I found the right size but different pricing from the one I bought with and was told to pay the difference...I mean how come I have to pay any pricing apart from the one I have on the same clothing, no color change no nothing different just the size? It doesn't make sense. Called customer care and still no different answer and I don't remember coming across such terms and conditions placed on their slip. I am so disappointed.