GSM-200 malfunction? (SOLVED)

[Edwin2008]

finally the visonic (powermax pro) is installed. Took some planning but it's working, for 1 week......
Suddenly i'm not able to use the GSM module. I can dial it and i hear the standard ringtone but i'm no longer able to switch the visonic on or off neither do i receive warnings etc.
Does this mean that the GSM module is gone or is there something else to try?

edit**
Suddenly i realized that i'm hearing the typical GSM rumble through a speaker set near the visonic, not being my mobile phone. I heared as a phoe that is having a connection problem so i placed the sim in a normal phone. Very fast i heared a administrative block, Huh? I was having auto refill & notification enabled. It appeared that the auto refill was set back to disabled and somehow a also did not receive a notification. Strange. Have dropped a question at the service department of simyo.