Wow, they did the same thing to me today. My kids and spouse have one account each, (4 total), on this IP.
I use only Elite proxies, and they froze all of our accounts for the same reason, "Auto Buyer", but I have never run the cheat/auto/ss/adopter/ or anything on my IP, only an Auto Pricer for my shop, because at times I'm too lazy to look up each item myself.
My kids hardly log-in and have less then 5k of items, maybe once - twice a month,
and my woman.... she has almost nothing on her account, maybe 20k worth of stuff and only plays random games and buys 1k plushies from user shops, never main shops.
Wow, that pisses me off. I'm going to unplug my modem & router for the weekend and let the IP get changed over.