communication problem

my mobile phone doesn't work the way it should. during the last days i had problems receiving text messages, frankly: i didn't get any. first i wondered, why people didn't write back. then big s. called me twice why i'm not at the concerted place and so on. now i found ou that some of my messages arrived, others not. ? at that time i knew something was wrong. i still don't know what's going on, maybe my mobile wants a new sim-card.
but not only that i missed meetings, i also couldn't pick up my mum who waited at the train station and who then had to take a taxi. :(