can you trust your service provider?

I have carefully monitored my package usage for the week 12 - 17 August. only 10 SMS's were send, however when I checked my balance, it reflects I only had 26 out of 50 still available? This means 24 were used, however where did the other 14 SMS's go to? This is how cell phone providers make their money? People do not keep track of the usage of data or any other parts of their package and when it runs out, you are then forced to top-up? Can I please get an explanation for the above as this just again a way how consumers are ******* by service providers