Is this a way to rob us of our money

I went to pay the interest on our laptop today 25th August, the cashier then gave me another contract which was dated for the 23rd of September, I phoned my husband and asked him if I must rather take the laptop out of pawn, because our pay day is on the 25th of every month, I the told the cashier I want to rather pay the full account because we don't want to take the chance of them selling the laptop, she asked me if I wanted to do another transaction and I told her yes!!!, she told me she can't do it, I must go and speak to the manager Jabu, he was very friendly, he then told me if I want to collect the laptop I must pay the full amount on the contract, I told him I paid the interest all ready, so he told me I have to pay the full amount that is on the first contract, so I asked him what about the interest I paid all ready he told me he can do nothing about that, something to the sort if they deduct that amount of the total owing the cashier wont balance on her till. So I must just hand over nearly R300 for free to cash crusaders, that is not acceptable,