I'd suggest trying to find someone at EA who knows anything at all about networks and how they govern their region locked servers. While the administrators can white list and block IPs just as they could to revoke player access in the event of misconduct, the database which each and every region locked server talks to will be controlled by EA. If the server administrators can't help you, then it's EA you need to talk to. The only other option I see is your connection bypassing the CGNAT and being given a public IP address, which I don't think they have the capability of doing.
Just like when talking to a customer service rep at an ISP about a technical issue...You need to find the technical people from EA that are willing to forward your case to the actual "specialist" team. Flip are great because the head of networks isn't 3 working days away in terms of being able to get an answer out of him, and he will give you a straight answer. I'm guessing that straight answer will be something along the lines of "It's EA's problem". Flip's network is non-standard. EA didn't consider that when designing their region lock system. Flip will need to give you a standard solution to match EA's standard region block system or the region block will have to change to suit Flip's non standard IP range.
I feel for you. I hate issues like this. Easy to narrow down the problem, yet so hard to find the right people to sort it out. If you manage to get anything from EA, you will probably be helping a lot of Flip customers. :)