Airtime disappearing umpteenth time!!

My airtime keeps disappearing immediately after recharging. This has happened too many times now!! Every time I complain about it they say it is my cellphone's software. I fail to see how this can have anything to do with this, and it seems these excuses to brush off the complaint. I will be moving to another service provider if this is not resolved within the next day or too as it does not make financial sense to stay on if every time I recharge my airtime it's as if chucking money down the drain. Just now I I recharged R150 and it disappeared.