Wonga is ruining my credit

I am really fed up with Wonga, I took a loan and paid it off in 2020 June, today is the 2nd of July 2021 and that loan still appears as open on my credit report, I recently tried to get a loan for a car and I was told that my loan with Wonga is ruining my credit. I have been calling wonga since last year asking them to send me a paid up letter and close the account. Every time I speak to a consultant they tell me that, it is done SINCE LAST YEAR! today I checked my credit report and its still open and my credit is still bad I then spoke to a very nice consultant today who told me that she wants to confirm payment for the loan that I paid last year! I mean really? its a different story with each consultant, one says that the payment has reflected but hasn't been updated on their system, one tells me that my account is a mess, the other says that she can't see the payment. I really can't deal with wonga anymore. My credit is not looking good and I get the same story each time I call, yes mam it has been updated. IT HAS NOT BEEN UPDATED! ITS STILL OPEN ON MY CREDIT REPORT. I am very very dissatisfied.