Hopefully, once you get the "good" unit & try it out, and see what it can do ... you'll be glad you got one !!
I understand your frustration ... but, if they send you a new unit BEFORE even looking at the bad one, and they're paying the return postage for the bad unit ... that sounds like pretty good customer service IMHO.
Check to see what software version it's running. If it's not the 3.6 version, get a micro sd card & reader and upload the update ... then download it to your unit. Then you can split screen over/under !! (see earlier posts for links to the update, and a link to a $6-$7 micro sd card/usb flashdrive reader)
... cp