Poor after-sales service

Settled my loan for a car I had financed in 2018 - however I had paid extra over-and-above the installment into the account during the loan term, the money was never capitalised and remains locked in the account. I've been trying to get these funds back.

I've tried phoning the customer support line - no one answers the phone, even after 15 minutes of being on hold (wasting tons on airtime). Emails have gone unanswered.

Miss one installment and the world must come crashing down, but nobody cares to honour a simple and rightful request from a customer who's operated in good faith.