tefal - Faulty item repair took almost 25 days

I purchased a Tefal air purifier a few months ago as I have wheezing and bronchitis. It stopped working for some reason, so I called Tefal customer and told them I would like them to repair my air purifier, and that they should repair it on priority because of my breathing problems. The customer service executive said he would ensure this information is passed on. The repairman came and took my air purifier, and they took almost ** days to fix it, citing reasons ranging from 'the parts are very difficult to get', 'the parts came to us damaged and we reordered new parts', 'the courier lost the items and it will take some more time' etc. As a result of their negligence, I was admitted in hospital and was bed ridden. When they finally fixed my air purifier after ** days, I turned it on to discover the air purifier was smelling very bad. I opened the item and found that the item was covered in dust, which is unacceptable because I bought this item to purify air, not to expel dust in my house. I called them and complained about this, and they just dismissed my issue saying that the dust and smell is coming because the item was unused for ** days and therefore it is normal. My response to them was that it was their fault that the item was gathering dust for ** days because they were supposed to repair my item within * business days (as most brands do) and that if they had stuck to their brand promise I wouldn't have any complaints, but they have dismissed my issue saying there is NOTHING they will do about it.