Colmed Debt Administration

Colmed contacted me about money owing 3years ago. re an accident that Vitalmed (ambulance) assisted with and apparently wasn't getting paid by the Road Accident Fund, so they approached me after 3 years stating that its a final demand and if no payment received, I will be blacklisted. Have been paying them, and should be uptodate with pmts. Requested detailed statements from them asthey are still demanding more money, but to no avail, they sent a statement just reflecting a much higher amount owing,that does not make sense at all. I've requested a detailed statement but to no avail. I've also requested a copy of the call recording as well as the manager to call me re the account, but to no avail. What to do in this instance? Is there someone like an ombudsman for these things that we could address it with?