my airtym disappears

on the 25th of July bought airtime for the cash value of R700 through my banking app bought an everyday gig for the value of R199 bundle which was 14gb which would give me 2gb times 7days which should leave me with the balance R501used my data to download some series and videos on youtube at around 23;30 my bundle finished which I understood but when I checked my airtime because I wanted to buy more data I saw that I was left with R66.00 which is strange because I blocked mysim from any out of bundle usage which means mtn is I would like to lodge a complaint my number is *** I need my airtym back for I need to buy data please which I use to earn a living how much of my hard earned cash I use buying mtn data what you guys are doing is ***** mu email address is *** i need answers i can not be cheated out of my hard earned cash my number is ***