Currently I use the Dialog HSPA Unlimited Package, I think it's really sucks up

coz most of times I got EDGE or WCDMA connection not HSDPA so the peak download speed is in most time around 384Kbps or 512Kbps and the coverage is not enough to cover the zone which I live in(Boralesgamuwa)
even Dialog says they provide 7.2Mb/s speed but I have never seen my connection's speed go up to 1.5Mb/s just till 1.5Mb/s I think now I really screwed up by this connection coZ I WANT THE STABLE CONNECTION ,WITH SPEED 512Kbps <<
when I chat with facebook then the connection is automatically disconnected in msot of times,, shit.!!! Yaluwo Okkoma tharawewi .!!!
SO NOW I REALLY WANT TO MOVE TO MOBITEL M3

Connection Is their anyone here who can tell me how do I use my HSPA (Vodafone)Modem that bought from DIalog with Mobitel M3 Connection (SIM).!
CAN I USE DIALOG VODAFONE HSPA MODEM WITH MOBITEL 3G SIM .???????
Plz Aiyala ,Akkala Ubala dana deyak thiyanavanam kipallako mata hangan inne-nathiwa,!!!
Ikmanatama ban .! mata Hadisi lat ekka tah yanna thinawa.!