Vehicle purchased with critical parts failing and no communication????

Extremely disappointed in my experience at WebuyCars I purchased an almost brand new vehicle from them a week ago it was a category A vehicle. I received it with a service light on the dash as soon as I arrived home the battery was completely dead sent it in for a service (at my own cost not even a week later) they inspected the vehicle and advised me the rear breaks needed to be replaced? This is a critical part that is needed for road worthy relevancy???? To top it all off Ive been in contact and the person I have been speaking to requested information from me I sent him everything he needed and he hasn't responded to me in the past 3 days???? How can this be possible? Claiming a vehicle is category A without ANY inspections done and critical parts failing less than a week later and only 50km put on the vehicle??