WHAT'S THE USE OF PRICE LOCK IF YOU TAKE MORE OF DEBIT ORDER???

Taking extra off debit order, Is this even legal? Do not think so!!!!!!!! I am on price lock (thank goodness it is almost over then I WILL cancel). My debit order every month is R988.50 (PRICE LOCK). Suddenly on 30 Aug 2019, my debit order is R1228.69. I know it is a small amount, but still that amount is MY MONEY. So I called the centre, the consultant said yes, there was a glitch in the system. Wonderful, so! Just think a glitch that takes approximately R240 extra from a 1000 DSTV customers. Nice way to make up some lost income DSTV. I was credited with R121.19 end of Sept 2019. I still have an outstanding credit of R119, sure my math is correct. SO DSTV, kindly advise when I will receive my money back either hard cash into my bank account or credit end of Nov 2019. Just tired of paying and getting useless answers from you guys and yes, cannot wait for NOT BEING A DSTV CUSTOMER ANYMORE, one less expense in my life.