Dissatisfied customers

I have a service plan with liquid capital and they are now saying that the plan has lapsed (which im still paying)due to me missing my 45000km service to no fault of my own as I was informed that my car service is due on every 30000km and it was actually said that my next service due is on 9 Dec 2017. I continued driving my car which is currently on 50000km and it started having a screeching sound which is the fanbelt, I then go into the Hyundai dealership only to find out that I missed my 45 service and that I will now need to for the service and to fix the fanbelt. I just feel that this is poor service that no reminders are send to their customer even if its just an SMS but nothing. I called their customer service line on Monday 28 Aug 2017 and the agent called Penelope was so unwilling to assist, I then request to speak a manager she transferred me to Thulile M who advised that she would escalated this matter to have the service authorized for the Tuesday 29 August as this all happened while I was at the dealership to book the service for the Tuesday so all that Hyundai needs is an authorisation number to proceed with the service but I have yet to receive any feedback when they said their get back to me within 4-6 hours today is the 1st September 2017 and still nothing. I emailed Thulile on Wednesday and advised that their 24hrs to get back to me still nothing and my car is still not serviced. The way this is being handled is very unprofessional. I'm very unhappy and worried as to what can happen now going forward as my car is still not serviced.