poor service

i have been using my mtn number for over 2 years then suddenly my number just lost network i thought there was a problem, today i call customer care i spoke to Lachita to my surprise i was told my number was deactivated and its given to someone because i was not buying airtime mean while i used to buy over R200 airtime on a monthly basis ,this is so unfair what MTN did to me ,people out there expect the unexpected with your mtn cell numbers they will be deactivated and will be given to someone else without you knowledge ai m so ****ed and irritated with MTN i don't know why did i get to use their network MTN is so unreliable, the list they could hv done at least was to call me and ask me to buy airtime i was going to do unlike just deactivating my number and give it to someone and thats a lie becasue i called my number it says the number i called does not exist to mtn network but on the other side its given to someone ,yhoo MTN hai no its so bad.