Horrable service from MTN

We took a business contract out on the 07/05/19 with MTN on a Sky deal for R1699 per month the first 2 months the contract went of at the normal price and the all of a sudden started going off with R2499. I started phoning them sending emails countless times and until today the amount is still wrong and this is not sorted out. I have asked I have shouted I have begged and still no luck from MTN. They are so fast to give you a contract but when it comes to a problem it takes them more than a year to sort out?