Extended Warranty for motor vehicles

Hi, I have been given the run around in terms of my extended warranty. When I initially purchase my vehicle from VW Strijdom park which is financed through Wesbank, I took out Unitrans extended warranty through VW Strijdom Park. Now that my warranty will come to an end, I contacted Unitrans to further extend my warranty. All Info was given to Unitrans Representative to extend my warranty through Wesbank. Wesbank has refused to extended the warranty from Unitrans because I apparently signed a part in my contract that said I don't want any additional finance ontop of the finance I have through Wesbank already. What I do find strange is that Wesbank can offer me extended warranty through Motorite (the Engine Room) and can add that to my current finance. So I ask the question, why can't Unitrans extended warranty be added to my existing finance but Motorite can. I'm extremely happy with the service I received from Unitrans and quite frankly Motorite does not cover as much as Unitrans. So I need answers?????