Bad customer service

I bought a dress @Kolonade end of 2020 then it didn't fit well. Mid Jan I send my niece niece to e credit it for me Pta CBD to be told se can exchange even though she didn't ask for another only to credit it. The beginning of February I went to Pta North mall they refused to exchange the dress bcoz the month has passed which I was not aware of (at the back of the sale invoice) I send the email also to the complaint dept with no success. I'm stucked with a dress I can't wear