As far as I know, you can only purchase the stuff it offers. For your case, I think you can try to send an email to onlinesales@dji.com for a further help.

Last week I was given the same coupon you describe for a warranty replacement of the Mavic and battery only.  They made it very clear that it was for that specific product only and couldn't be used for anything else.  I'm curious if you are able to work anything out otherwise...