Frustrated customer by Finchoice

I had a loan account with Finchoice (acc no. ***) which I fully paid in March 2019. Last week I app**** for a bond and they advised me that they can't approve due to affordability because I owe Finchoice. I called Experian credit bureau and they advised me that I must contact Finchoice and they must write them an instruction to remove the account as it shows open/active on my credit record and they don't want a paid up l;letter, they refused to give me their email address and said Finchoice will know where to send it. I have been on a call with Finchoice the whole of last week and I can't get any help from them, they asking the email address from me which I can't get from Experian. I spoke to a manager there in the legal department which offered to make sure my query is resolve and someone will call me, till today i haven't received a call, I sent emails and no response, all I get is an SMS to say my query is resolved which is definitely not resolved. at this point I do not know what to do, I need to buy a house but i am not getting any joy from Finchoice and Experian, instead they are sending from pillar to post forgetting that I need a place to say and i finished this account a year ago. I am deeply hurt because i have settled this account last year already and I never even missed one payment, I always paid them on time. Please help me.