MRP are *****s

Got a cellphone contract with them and a clothing account. Cellphone supposed to deduct R99 pm and clothing I pay it. Recently saw my statement on clothing account had airtime purchases (I've never bought airtime from mrprice and didn't even know you could uisng clothing account), called in and I was told no I'm the one who's bought airtime to my number, even though I've told them I've never bought airtime. Anyways my mobile account gets debitted more than the R99 and when I ask I'm told, it's because I reached my limit and then I used out of balance what what, this I can believe (even though I've called in endless times to set my call limit at R1). So they are saying I'm calling more than my allocation which is fine, they can debit that amount but now they saying I also buy airtime on top? Why would I do that if I can call endlessly...? Really disappointed with your services