[Resolved]  Elica — Installation person not a professional

I ordered a chimney from elica through Amazon. My kitchen is very easy to install the ducting pipe aluminium required is very less as there is already a exhaust fan hole immediately over the stove almost parallel to the top end of the chimney. But he is asking me to put a new hole on the top saying the chimney will reverse flow the smoke if the exhaust pipe is near and I don't understand the logic and science of it and I feel he is just fooling me around as he might not earn much from the installation as no extra ducting is required. I also cannot drill a hole in the kitchen as the beam of the building runs through it. I am also not able to return the product as Amazon is giving only replacement not return and no help from elica inspite of repeated calls. Either they can send a technician who is not money minded or take the product back and give me a product that is compatible with my kitchen.