Viessmann Service Unresponsive to Air Conditioner Issues

For the past few years my Viessmann air conditioner, just not giving me what it's supposed to...there were holdups in getting the air conditioner's gas tank refilled because of the pandemic. When I originally contacted their service, they said they'd be right over as soon as the gas supply problem was fixed. My air conditioner continues to malfunction, and the situation is becoming increasingly frustrating for me. Every time I've phoned their customer care line over the past two years, I've explained the matter and been assured that my case would be given top priority and that someone will be sent to fix it. However, no professional has arrived at my house to remedy the problem despite their assurances. It's been an ongoing loop of frustration, hopelessness, and waiting.