Seeing as their FC got banned, I wouldn't trust any of their ranks as they might panic scam. You can use someone on Sythe who has a lot of vouches to exchange your gp for you.
I used them not too long ago, but it was only for ~10m -15m so wasn't too worried. Your best bet is here on Sythe, find someone willing to do straight exchange.
There are plenty of people on here that do gold swapping, as well as plenty of users on RS. If you know a trusted FC, use them, or you could use a trusted member on here.