BSNL 3G Dynamic IP Issues?

[Quasizero]

I am using a Micromax MMX300G modem with my BSNL 3G connection. Since a week or two I am having problems with using Filezilla (FTP), my online banking and even logging in to website admin panels (DirectAdmin). Browsing and checking e-mail work just fine.When I was looking for a possible cause I noticed that my external IP changes while I am connected. I always thought that a dynamic IP address only changed when you reconnect.So right now it is switching between 218.248.80.59 and 218.248.80.51. When I reconnect it starts switching between 2 other IPs.I tried using BSNL Customer support, without any luck. So the question is if anyone can tell me if this is normal behavior for BSNL 3G, and if not, how I can solve this little problem of mine?I'm new to this forum and not an Indian, but I thought I would try my luck here. Thank you for any input.