OM loan settlement " oversight "

hello Peter

In November last year I believe on the 29th, I decided to settle 2 loans I had takemn out with Old Mutual, as the norm I called them for settlement amounts and the settlement conformation letter which I received. After concluding my conversation with one of the old Mutual service agents and was given the requested settlements amounts, I proceeded to pay both amounts. To conclude all of this on the 3rd January I contacted the Newtown branch which was the very branch where the loans were taken from to confirm payment, which I was assured had been settled. I have recently found out that I'm in the process of being handed over due to one of these loans, I called the OM legal department and have been told that this wasn't actually due to non payment but some sort of oversight which wasn't necessarily either of our faults" the sales agent who assisted with the settlement information or me " in fact she wouldn't have been able to pick this up at the time. my concern here is, I took a decision to settle these loans which means I had intent and when I asked for the settlement amounts believed " if I settled these amounts that would conclude my business with OM" this has now turned to be a legal pain in the ASS and sounds to me OM believe they are not in the wrong neither am I however someone now needs to pay for this oversight and they expect me to do it - please Help.