BIS not activated on BB, & airtime used up as data

late Jan 2015 i upgraded my BB (with BIS) to a 9720 for BIS, & 2 days later my remaining airtime on my prepaid contract was used up. it was close to top-up time so i didn't worry too much but i always get thru whole month on R100. i got my new R100 airtime on abt 27 Jan, and 3 or so days later half my airtime was used up again so i called mtn. settings were fixed by someone. approx 8 days later again i checked airtime & it was all gone again. called again & went to 14th ave, & was told ALP settings ? were out again. went to mtn cresta & branch manager got it sorted as i was tired of holding on forever & then being cut off. settings were fixed again. he requested as did i for my airtime to be refunded as i am on BIS and airtime should not be used for data-whatsapp/bbm/fb. 2 months later & no airtime refunded & i have been told over & over that this was MY FAULT? i asked for a cell with BIS & DO NOT STREAM & DOWNLOAD, and since it was fixed, an entire month has gone by & i only used R70 in the entire month on calls. BIS is now active. I expect my airtime refund from this cellular giant. I am not asking for R1 000 000, but just R100. Please can someone sort this out. Kim