Pathetic service from Mercedes Pinetown

I have owned a Mercedes for over 20 years. I have renewed them as at intervals so that I keep the warrantee and maintenance intact. I have had great service from Mercedes in the past years until the last 3 years when they degraded their client service. The pinetown branch is one of the worst branches one can deal with with service agents and managers don't recognise the value of their customers. The last visit being a few days ago again infuriated me. I have booked the vehicle for service as the service light came on. I was given a date and took it in. A few hours later, the service manager called me to advise that they don't have the cwrtai spares like filters to conduct the service and that I was bring the vehicle back when they advise me. The concwrn is that once the service Iight comes on that the vehicle needs to be serviced. This did not happen. They in swrious contradiction to what they normally do to ensure the owners are not at risk should components fail.the manager also advised that they only get spares once they inspect the vehicle. So what happened to the electronics of the vehicle that indicates when it requires maintenance.The indication is that they are cutting costs and placing their customers at risk. We have been charged upfront for the maintenance plan. Now these vehicles are not cheap, we have paid a significant amount to own a Mercedes. I feel highly let down and feel that Mercedes have become shoddy and unrelia2ble. To top it up is the pathetic behavior of the service manager at pinetown whom tried justifying their bad service and poor planning . I asked him to inform his his manager that I needed to speak to him/her. No response from the senior management. I feel that I'm at risk with my vehicle as without proper maintenance could result in faults surfacing once the plan is over. They will be very quick to reject any claim.