Bonus sms ****. Sms working unless airtime on phone

If I recharged rather please do not give me any bonus sms because they won't work. Sms only goes through when I have airtime. I had 58 "bonus" sms. And I needed to send 1 and it does not work. It cost me to buy emergency airtime unnecessaraly to send one sms. What is the use of a bonus sms when you can't use them.