Arrears amount

Ford credit and their consultant who does not know how to do their job they harrass me everyday calling me and telling me that I am in arrears, In august I payed R10000 and advised them that they should take the arrears amount on that 10k which was extra payment of the car they keep on telling me I did not pay but on my statement I can see 10k was received please take your agents to training clearly they don't know what they are doing