Closure of Vehicle Finance Account

I sold my vehicle last week Tuesday 13/02 to We Buy Cars, the vehicle was settled immediately and directly by We Buy Cars as per the settlement letter received from Wesbank on the 12/02. On the 14/02 I checked my Wesbank account and the payment from We Buy Cars reflected, however there was still a balance outstanding so in a panic I phoned Wesbank and was assured by the lady that everything was okay as the outstanding amount was the interest saved from settling early and the account would be finalised and closed after 5 days, no mention mafe of proof of payment. Then I started getting emails requesting the proof of payment so once again Wesbank was contacted and once again I was assured Wesbank did not require anything. Then I received another email this morning from Wesbank requesting the proof of payment. Another phone call to Wesbank and this time we were told Wesbank needs the proof of payment to finalize the account. I'm really confused, why do I get told 2 different things by 2 different people and what I really don't understand is WHY Wesbank needs the proof of payment if the funds have reflected in their account since last week already and why has Wesbank NOT contacted We Buy Cars for the proof of payment as they are the ones who did the direct payment? I have requested the proof of payment from We Buy Cars 3 TIMES now and am not having any joy. So please could Wesbank give me the proper information once and for all so my account can be finalised and closed.