vwfs

am disappointed in Vwfs, and am still failing to understand what is going on even now, i made several calls and am being sent from left to right and no one is giving me the correct answers, on the 7th 04 2021, i requested settlement amount, and they sent me settlement amount 2 days later, as per their settlement amount i was left with R24058.52, i paid the exact amount on the 12th 04 2021 and i sent POP on the 13th 04 2021 to their email that they gave me, few days later they responded to say they recieved POP, of which in my understanding my account was supposed to be closed before 30th.04.2021. on the 1st 05 2021 they debitted in my account same car installment, and i phoned them sameday and i was told the money that i paid is not reflecting, i have find it impossible as the bank takes 24hrs to 48hrs to reflect, and mine its 2 weeks and yet is not reflecting their account, i used their account number plus reference number given, i phoned again and i was told they charged me interest and my account is still open. am confused because i paid off this account. another email that i got was to say i need to pay R350 its for change of ownership that one i dont have a problem. i will pay it. all i want is for my account to be closed and i need a settlement letter to sure that my account is closed. i dont understand why am i being charged interest while i paid off this account.