leather bag lady

My husband and I bought a Tiva unit from the Hamilton RV show in Ancaster a couple weeks ago. I was hesitant to buy one thought it may be too hot for my small she shed. My shed is fully insulated and finished inside. We were told by the salesman that the different settings would make it easy to control and that the heat wouldn't be too much for my small space. My husband installed the unit. We gave it a good hour to heat up my shed. It was a cold evening. The heat on full blast didn't even come close to heating my shed. We called the salesman the next morning not even 24 hrs after we purchased it. He told me to aim the unit to the floor (which it was already) and that really the unit should be installed no higher than 6ft for the best heat. This will not work in my space I have floor to ceiling shelving. I texted him to make arrangements to return the unit. We were supposed to meet the following weekend on his way through to a Toronto show. We have heard nothing from him. This was alot of money for us $450. Not sure what to do next. We need to return this unit which is in as new condition back in the box. I would be very wary about buying one of these units not only from a non starter point of view as a heater, but very poor customer service.