False reports to Credit Bureau

I did an EFT transfer to vodacom to pay my account on the 31st of October and when i checked my credit score only to find that it has decreased. When i investigate Vodacom has reported me that i was in errors for 1 month. When i called Vodacom they indicated that the amount was not assigned to my account yet i've used my account number as reference. I further went ahead and cancelled my contract with vodacom and paid the early or premature cancelation. To my suprise the 1 month in error still on my credit meaning vodacom did not clear it and still indicate that i have contract with them. I am in a process of buying a home and vodacom really messing with my credit yet i don't owe them anything.