Bosch Washer Short Circuit

I've been using my Bosch dishwasher for about 2.5 years, and recently it started experiencing electric leakage. I immediately contacted Bosch customer service to register a service request. Today, I received a phone call from the service representative. Without even inspecting the appliance, the person claimed to be a service technician and diagnosed the issue as a problem with the building's grounding system. I explained that I haven't encountered any such issues with other electronic devices in my home, but they insisted that it's a common problem with dishwashers. It's the first time I've witnessed a diagnosis made over the phone without the technician physically examining or testing the appliance. Moreover, they demanded payment for a home visit to inspect the issue, despite the appliance being under warranty. It's unacceptable for service providers to charge for warranty-covered repairs. This disregard for safety in handling electrical matters is not what I expect from Bosch. I'm disappointed with the individual posing as a service technician and with Bosch as a brand. I urge for a prompt resolution to this matter as electrical leakage is a serious concern.