Multi choice

Good evening My story is..am usually paying access on dstv and its 129 per month..so last year July they gave me a discount to pay 109..so the discount is over I should be paying 129 this month..when I check my balance they say I should pay 321..I don't know why that much and I asked them about that amount they don't give me a straight answer..they are telling me that I was paying a short amount..so I tell them that I was given a discount that's why I was paying 109...please help me guys I can't pay that amount on access...