Rivas are good
batteries, generally speaking. I own and use them all the time.
How old were your
batteries? Were they still under warranty? Where did you get them? And how did they die? If they both died prematurely and at the same time, I suspect a faulty atomizer that killed them both. You could check your atty with a multimeter... Anyway, I would first contact your vendor and ask for advice.
I'm not familiar with ivape, but I checked their website and noticed that they don't carry any Rivas. The eGos they carry are not the Joye eGo batteries; their eGos ar made by SLB. I'm sure they are just fine and if you need to get a replacement right away, I would probably get this kit:
DSE Ego (Black) | Starter Kits | iVAPE
However, you don't need to buy a whole new kit if you don't want to--just grab a couple of their eGo batteries; you can charge them with your Riva charger and your cartos and atties will work just fine on them, too. It looks like they only carry eGo-T spare batteries, but that's fine. Those are the original Joye eGos:
http://ivape.net/index.php/Batteries-and-Chargers/Joye-ego-T-battery-650-mAh-White.html
Oh, and if your atomizer indeed killed your Rivas--DO NOT USE IT ON YOUR NEW eGo BATTERIES!!!!! It will kill them too!!!!
Good luck.