Toys r us - waste of time

So my baby is 6 months old and I go to Toys r us to buy her car seat via the discovery vitality option. Six months I got an email from discovery and was advised to print it to get my pack - this I did and for security reasons, deleted the email. Got my pack, all good. Six months later, I go to Toys r us with the voucher and complete all the details behind it. I get to toys r us and they tell me that need the original email! Really! We have 3 years time to buy the car seat - I told the manager I deleted it and refused to help any further - i handed the letter in to toys r us already - why want it again if I have the card to complete!!! Now I have to source the letter again, then, spend more petrol and parking fees again! Who will compensate me for that? This is a Toys r us problem! They seemed phased as it just meant they don't need to take responsibility for accepting my letter 6 months ago