Receiving sms that am out of data

Its will great disgust that i write this almost every week i will receive an sms from MTN telling me that i have run out of data and when i check data i still have data.Just like today i had 77MB of data but they send me an sms telling me that am out of data.To my surprise my applications where not working due to the lousy massage send by this company.This is really degrading for a paying company as it clearly shows that this company wants us to subscribe to their contract as such things never happen when you are on contract when on prep aired this appalling services is rendered.They need to fix they pathetic billing as this is really getting on my neves now.Am even thinking that other people from other networks don't experience the same service we get from MTN.This has been happening for over 4 months not and i have been quiet now its time to act.