Unsolved query going on 3 weeks

I am a first time customer with Rain and received the router (free to use) the first week of April. The monthly premium is R529 however when it came to end April, the amount of R564 was deducted. Obviously i queried this on 01 May, its not a huge difference, but i am a single parent and it makes the worlds difference to me. I got no response from them. I queried again thereafter and finally got a response 10 days later. I did not however get an explanation of WHY they overcharged me on debit, only the following: "You were billed 969 and credited an amount of 405,57 was minus from that wich gives the amount of 564" i have no idea why i was billed 969 (where did that even come from) nor what the 405, 57 deduction was or how it ends up with 564 deduction. They clearly don't care to rectify or respond, because its a whole 6 days later again and i have sent another email. I heard so much bad things about other places, honestly thought this was going to be the one. Looks like i was wrong