Beko Canceled My Service Appointment Last Minute Due to Too Many Products

I scheduled a service appointment with Beko for between 5 PM and 7 PM, but now they want to cancel it, saying the time is too late and they have too many products to deal with. They want to move the appointment to another day, but I don’t get why something that was already set up can’t happen just because they’re overwhelmed with other stuff. It's been 3 days and I'm still stuck without a solution, which has been frustrating. I'm disappointed with my choice of Beko because I didn't see this kind of treatment or bad service coming. It's annoying that a brand like that didn't follow through on what they promised.