Firstly I would check here for some simple ideas. I use Xbox 360 so I have never tried the PS3 support tips, but there were some useful ones for Xbox 360 at times when I have consistently had trouble connecting online.
http://support.ea.com/cgi-bin/ea.cfg...p_new_search=1
As far as TW vs EA, I have Comcast, but I did have a situation like you where Comcast was blaming a problem on EA and EA was blaming it on Comcast, and others near me with Comcast were not having a problem. In my case, I was able to get oline, but I was getting dropped from games every time. The problem turned out to be with Comcast (despite their initial denials) because I was losing packets consistently (maybe 3 packets out of every 100). Not enough to kick me off Xbox Live or really affect general internet usage, but too much to allow the EA server to keep me on. If you have a PC on the same network as your PS3, you might try "pathping -n 100 easo.ea.com" and see if you lose any packets.