Poor customer service

I took my car for 120,000km service in April 2019 and at the time my car was on 126,000km. In September 2019 my car was showing a warning sign ''routine service required''while its only on 132,000km. I called CHM Mitsubishi West to book for service and i was told that its too soon, the car is only due for 135,000km service. I was advised to call CMH The Glen to reset the reading. I then called Mitsubishi The Glen and told them about the warning sign and the lady i spoke to told me to bring the car the next day, so that they car reset the reading. The day i asked my husband to take the car there on my behalf and he was told that we need to ignore that warning sign, its just an indication for the next service. I called The Glen and spoke to Angeline (service dept manager) - she told me to ignore that light, even though i was not satisfied about this, she just closed the argument by offering to put petrol on the service. 1. Why was i told to bring in my car, in order for the warning sign to be reset? 2. I was highly inconvenienced, because i had to cancel my meetings, for that day, spent petrol to get the car to he Glen and only to be told something that they could have told me on the phone when i called a day before. 3. If its just a warning sign for the next service, why isn't it showing me how many kilos or months till the next service? I'm so dissapointed, i pay a lot for my car - just to be played around like this. I just want this warning sign to be removed, so that i can sell this car and part ways with Mitsubishi.