Two weeks ago I started getting 3G in my area, the signal is weak, and from time to time my internet connection disappears, see:
I have noticed that the data counters are no longer tying up with the values Windows reports.
Today I finally got to the cause of the problem, it seems that the card remembers the data counters when the signal dropped, so every time you connect thereafter the counters start with the amount of data you had previously; if you manually disconnect and re-connect the MTN F@stlink software happily adds the original amount plus the new amount to the total. The only way to escape this is to reset the card or your computer.
I then experimented communicating directly with the card using Hyperterminal and found the fault does not lie with the MTN F@stlink software, but with the firmware on the card itself. Once the connection had dropped, I queried the values of the data counters with the AT^DSFLOWQRY command and saw the values as they were when the connection dropped, I then cleared them with the AT^DSFLOWCLR command and verified that they were all zeros with the AT^DSFLOWQRY command. As soon as I re-connected the data counters started where they were when the connection dropped.
Unfortunately I think this is not going to be easy to get resolved, Huawei do not reply to technical queries sent to their site, and even when a problem has been resolved, for example the issue with USSD commands, they happily dish out the fixed firmware to other network providers but haven't yet passed it on to MTN. One can't even download firmware upgrades directly from their website.