Poor service from multi choice

I took a promo deal in September 2018 for premium which is running till end of March 2019. I've been paying R789 from September till November and in December the system didn't automatically update the promo on my account and had to pay the full amount. I was told I was going to be paid the difference and had to call in again from January till date for the promo to be activated on my account. My account hasn't been credited since I called in in January. None of the consultants since January till date have assisted me with the query.