Vodacom just can’t get it right

Dear Vodacom, after my last complaint of you charging me my 24 month handset installment after the 24 months have passed, I finally received my statement and 2 credit notes today. And unsurprisingly, it is not correct. On my statement you deducted the one credit note from my January bill, but the full amount for January already went off via debit order on the 2nd of January. So instead of deducting it from the full balance, you should have given me that full credit. Please get back to me asap, because this is really ridiculous. How many times must I now waste my time trying to sort out this problem??