Emax / Max Electronics review: Customer service complain

I have purchased an apple series 9 watch 45 mm as a gift for me wife on 25th Sept, however when my wife saw the watch she wanted the 41mm dial, please note I have just opened the box to see the product and not paired it with any phone or done any settings on it . On 26th I want to the mirdiff store and requested for an exchange and to my surprise I was refused saying that as per policy if the box is Opened they can't exchange

First of all the salesman during sales should have informed me about this, secondly I was given a box with no seal and at the time of exchange they inform me of a seal pack, and thirdly the watch had no damage and was in its original packaging , which is mentioned on the receipt

Then how can my exchange be denied

This is absurd and it has to be resolved by exchange,

I am within my 7 working days and I have the product in proper original packaging. Then why am I told no for an exchange