Incorrect billing

My sister bought a washing machine and electrical stove at ok funitures at mount frere unfortunately she lost a job and was unable to pay then my mother made an arrangement for payment and honored her payments as arranged but ok came to take the stove at home and we thought its bcoz of areas but to my surprise when my mother contacted the accounts department for settlement she is still paying for the stove that was taken but washing machine is still there it was not taken.