MTN ***** or service provider?

I took out a data contract, which I receive 40gigs a month.

Iv been receiving the 40gigs since June last year. However two months ago MTN starts only crediting me with about half.

I am paying for the 40 but get half of what I’m paying for. Iv been calling customer service for the last month and a half and still no feedback.

How can you give me something different to what I signed for? If that’s the case I want to immediately cancel!!!!!!!

This is bull****. I either get my backdated data or money!!!!