VMS Construction and Plumbing review: VMS Construction and Plumbing

I would like to register a complaint against my contractor whom i hired to renovate my condo. Given below is the instance that i would like to report and request you to assist me.

We installed an air conditioner based on the contractors advise and now it is not effective enough. We now need to change the air conditioner to a bigger more expensive one and the contractor is not ready to replace the old air conditioner and asking us to pay the whole amount for the new air conditioner. We acted on her advise and now she is not taking any kind of responsibility for it. Also, when we asked for the warranty for the air conditioner they are not giving that to us ... it has been few days and they are not giving us the warranty and hence we cant even sell the unit and use the money to buy a new one.
Kindly let me know the process for registering a complaint for harassment and possible fraud as i think the air conditioning unit may not even be authentic Career as they are not giving me the warranty.