Which traffic accounting and user blocking system should I choose?

Question

Billing systems

Good day.
Given :
Satellite Internet
Limited number of traffic per day
Required :
Shaping the channel per users
Counting traffic by users
Authorization by IP + MAC
Cut off users who have gone beyond the traffic allotted to them for the day
Statistics (netflow support is desirable)
Reflection NAT (NAT Loopback) is when from within the network you can access an external address and work through forwarding.
The device is "all in one", because on the example of billing for Mikrotik (external) - if the billing server crashes, the Internet suddenly becomes unlimited. No billing = no internet. That is, the server is the gateway.
IPIP or GRE (preferred) tunnels
OSPF support
Desirable :
Ease of deployment (at least relative). I'm not a Linux user, but I can tinker with it.
Tried tmeter - screw NAT does not support NAT Loopback and there are jambs with multicasting. Previously, everything worked on mikrotik, on scripts bypassing queues, but, firstly, after a reboot, all statistics are reset and users who have chosen their limit are again "in the ranks", and secondly, problems with the Internet began and, for the purposes of the experiment, it was decided from mikrotik to parts of points to refuse.