It is a mixture of everything, it is more a residency problem than anything else, I will look into opening up a case at CasinoGuru. Is there any other arbitration website you would use, or better to keep everything through one channel?
Umm... There are other arbitration site that as famous as CasinoGuru in facilitating dispute mediation, AskGamblers, but Rollbit is not available on AG. And there are other site that might have Rollbit, like casinoreviews [formerly ThePogg], I haven't check if they're on them, though, nor really familiar with their reputation in dispute resolution.
IIRC, there was an inquiry by other member far in the past to Rollbit to where can someone raise a dispute, and they suggest to raise it to their licensor. So, I think your option is between CG and their master licensor.
And no, it is not recommended to raise to both simultaneously. The master licensor is seen as the final path. When CG learn that you've escalate to their licensor, more likely than not, they will cease from mediating.
So it's completely your choice, either to have CG a try or to directly go to their licensor.