It can be really frustrating to hunt after fake apps when not even the provider of the original seams to care ...
Here is our attempt at reporting a fraud at https://capital.com
Discussion
These default customer support channels are just not built for this type of request. Maybe call their phone hotline and ask for an escalation due to a security issue?
For all I know they might escalate this internally but certainly their staff should have protocols for this. After all, people that do lose their money to these apps also do contact them.