Since it's a seam leak, I'd question the integrity of EVERY seam in that piece. The operator or a poorly maintained/adjusted machine could be the cause of the issue and might extend to ALL seams, so I'd suggest replacement. You don't want to get it 3/4 full and have the side seam blow out.

Where and when did you purchase the pool? If you put the purchase on a credit card, you my have some leverage through the CC company. Most big-boxes have a 30 day return/exchange policy.