If you know that tweaking did not favour you here is unlimited browsing for MTN sim.
Download :
Simple Android sever and Auto proxy then you Follow this instructions:
Create New APN settings On Your Phone As Follows..
Proxy: 127.0.0.1
Port: 8080
APN: Web.gprs.mtnnigeria.net
Save And Activate it, set the new created apn as your default settings.
Go to simple server and configure the settings:
==>Proxy host: 10.199.212.2
==>Proxy Port: 8080
==>Injection Method: get
==>Injection querry/url:http://mini5-1.opera-mini.net
==>Injection Host:mini5-1.opera-mini.net
==>Injection line: press your enter key 4 times
==>Buffer size: 8092
==>concurrent connection:10
==>Log level: debug
Close the settings
Settings for auto proxy:
click on then option button to view the menu option then click on creat new proxy...the proxy host:127.0.0.1 proxy port:8080 proxy type: HTTP then save and connect....ENJOY your free unlimited browsing.

It seems too have a 3gig data cap, so if your download stops or you are unable to connect, simply insert another mtn simcard to continue