This network is not good

Telkom uses my all net data bundle during night surfer hours. Also constantly receiving SMS's that I have run out of data, when in fact I have plenty. I found out that if I change my data connection manually on my phone from 3G to 4G or visa versa - then internet works for a while, then SMS again and I get cut off and have to manually change the setting on a phone from 4G to 3G. Something is really wrong with their system and they are not fixing it. Its been many month of this nonsence. Now they calling me to take an upgrade on my contract. No, thank you. Please don't phone me, I won't phone you either.