Mtn cheap data ****

I have a 50gig data plan with mtn.but I was given only 20gig and told the other 30g was a promotion. I have had this contract for 8 months now. Please be aware of this **** mtn is pulling. Don't fall for it. Its affordable data plans are a way to rope u in.i have been ****med and I'm taking this to the ombudsman don't fall for the same ****.