BMW 320i Overheating - Full Coolant Service not done/visible on all invoices carried out.

I've serviced my vehicle at BMW East Rand for over years, with an exception of one service that was done at BMW The Glen. I've had a full maintenance plan to 100 000km + an extended maintenance plan with a 3rd party that covered service and full maintenance including parts replacements. After looking at the entire service history of my car, I dont see an indication of a full coolant service that was done on my car. I'm taking checking/replacing the water pump, heat exchanger, line coolant, gaskets etc. After doing my extensive research and discussing with BMW technicians, the entire full coolant system must be done at least every 4 years. This means, by my 97 000 km service, this should have been done and if so, this service/maintenance and pats replacements should come with a warranty. A few weeks ago my car started giving me indications of a coolant shortage so naturally, I kept topping it up. Now my car is overheating and I'm not driving it, leaving me without a vehicle. All I ask is for BMW to do the right thing and fix this coolant issue which has now resulted in an overheating issue and to treat customers fairly. This is such an inconvenience.