Ridiculous service

I have been renting my car since 2019 had few hi-cups here n there with finance department n the workshop staff. Since the new finance lady I was told I owe money for what I asked if a debit order returns unpaid they charged me for that I asked was this in my rental contract no then how do I owe u if this was not brought to my attention 🤔. A month ago took my car for a service after inspection I agreed to the full service wow before I could come to fetch my workshop guy sends a message telling me I can't fetch my car before I pay my outstanding amount with finance. Was this also in your imaginary contract. I have been paying rental n insurance but each time I phone the workshop to assist I was charged for repairs. Am getting threats every month if I don't pay the R1090 they'll switch off my car which they twice did while I was driving without notice.