Their own FAQ states:
# Can I access my email o'nce I have reached my credit quota?
* No. You will have no internet or email access as your account is inactive o'nce you have reached your credit quota, and will be reconnected o'n the first day of the new month unless you contact the call center and have been granted permission from the Sentech call centre.
So instead of cutting me off, you idiots, how about rolling over like you're supposed to?