bad experience with mtn- especially with their data services

I am a customer for mtn for years. I have been with the network since my first cellphone and my first number which is the one I am using. I had bought data from mtn as I usually do monthly and the data has never expired let alone anything until it runs up. I had bought 2gb last month on the 25th march 2016 as I want my phone to have data, and I receive free data on top of that.Last night I slept with 1.8gb and woke up with the same amount of data and I went on to facebook for 5 minutes then went to whatsapp, then 20-30 minutes being on whatsapp there my phone looses network coverage and i can't seem to send messages on whatsapp only to find my data gone. I call mtn and I get through to a lady called Nontando in polokwane where I feel very unhappy by Nontando's service and I request her manager and she drops the phone on me. I call back and I get through to her again when I ask why she dropped me she cant explain properly. I request her manager and Ephodia comes and she tells me she is going to call me back which means another hang up from them. I got frustrated with them asking why are they hanging up on me instead of helping me. Ephodia calls me back and explains what I don't understand, why should data expire before it even depletes? Why is mtn eating us up? I hardly use my data because mtn's network coverage doesn't support some areas, I can't use data during the day because I never have signal. I am very unhappy and sad with the service mtn has provided me, I never hesitate, I buy airtime I buy data I buy everything but if this is how mtn treats its customers then I don't think I am a happy client. I am not the first one to complain about data problems & coverage problems with mtn but I have had it because I have also kept quiet because I support mtn. I am very unhappy that I don't have data because of mtn's lack of appreciation how can 1 buy so much data to be taken away from you? Isn't data suppose to expire when it depletes. We receive bad service through out from MTN and they expect people to stay loyal to them, no wonder they are loosing clients to competitors is because they lack customer service. MTN is a disgrace of a service provider... I want my data!!!