I regret having contract with Telkom

I have 24 months contract with Telkom Mondo, paying R320 monthly, they give me 10 gig daily and 10 gig nightly, but my daily gig has been depleted, only left with 10 gig of night, but to my suprise i cant use it. I tried to wait till 00:00, trying to log in and to my suprise this minutes cant work at all. So please what am i paying for? Am i ****med?