Poor customer service

A few days after buying a jacket (size:3/4)for my daughter (3.5yrs old) from Zara Kids clothing store in Tygervalley, I returned to exchange it for a bigger size, but misplaced the proof of payment, however the price tag seal was not broken, proving that the garment was never worn. I was shown away without a solution to my problem. A couple of days later I found the invoice slip, but was away on holiday at the time and could therefore not return to the store immediately. I visited the store again today with the invoice AND the price tag stil not removed from the jacket in the bag I was given with my purchases. The branch manager then pointed out to me that the jacket was bought 35 days ago and that the exchange period expires after 30. As a loyal customer, I merely expected loyalty in return. All I really want is the beautiful jacket for my daughter to wear and enjoy, the exact same jackets are still in stock, however Zara was not interested to accomodate me.