Bonus Vouchers

Modnation Racers Amazon Pre-Order Voucher help?

I pre-ordered modnation racers on amazon when i heard that you get a voucher for a "ratchet and clank" add on set. (i ordered it back in march) when i got the game yesterday, the voucher was not in the box (but a bonus sackboy character was.)

When or how will I get the voucher code? Will i get it in an email? will it be shown on amazon? will it be mailed?

they usally send it within a month or two. That was the case with both my heavy rain and bioshock 2 pre order bonus.