FNB vs WesBank

I moved my bank account to FNB 8 years ago. After initially receiving good service I decided to take out a home loan with them. After receiving more good service I decided to buy a car through WesBank, and then two more cars through Volkswagen Financial Services underwritten by WesBank.

Why is it that WesBank service absolutely sucks? And why after buy 3 cars with Wesbank and having a good relationship with the FNB family do they try their luck every time by approving car loans at silly rates of 16%??

I am in the process of buying another car, but it looks like the finance will be done through ABSA this time. They gave a reasonable rate to me as a relatively unknown customer to them. WesBank/FNB does not seem interested in retaining my portfolio.