H&M = worst customer service

I visited H&M V&A Waterfront yesterday to exchange an item which was bought as a Xmas gift for a teenager. He did not like the color and therefore the exchange, he did not even try it on and unfortunately due to circumstances I was not able to exchange the product sooner. The cashier explained nicely that the exchange date was within a month from purchase, I explained to him and his supervisor that I was not able to. The product had all the tags and is still for sale in the store, I then spoke to the manager on duty, Rhonda, I did not ask her surname and when I asked the cashiers they did know her surname ... She told me that I had to call a call center who will decide on whether they will allow me to exchange the item. Is this deliberate to frustrate customers, she did not even give me the call center number before she walked away. I find it disappointing that a store manager cannot make an assessment of the situation and make judgement call on the spot. The item is still in stock, I was exchanging it for a different color ... this is the worst customer service I have come across.