Unknown debit ordet

I just had my first unfruitful call with a cell c customer agent. There's a 183 debit order that went off today, I am asking what is it for since my new contract which is supposed to be pro-rata since I just got my simcard now is 129. Noone at cell c knows why the money was debited from my account. I thought they have the system to see these things, will I be wrong to reverse the money since I don't know what is it for and they also don't know what is it for