Bayport losn

We had a loan at Bayport so in 2014 we went under debt review in Aug 2019 debt review paid our loan in full Ive got all the proof of payment but now Bayport keeps on phoning us and say we still owe them R3800.00 the letter they have send us said outstanding balanca is R59429.90 and debt review paid them R77000.00 so how can this been resolved please