Employment Law Questions? Ask an Employment Lawyer.
If you are an independent contractor, you can legally be terminated at any time, as long as the employer does so in accordance with your IC contract. If that contract does not limit the employer's ability to terminate, then they can terminate 'at will.' There is no requirement for them to be fair in that decision to terminate unless the IC contract specifically states that they have to do so.
Really, the only thing that you can do here is obtain the IC contract and make sure they follow any provisions that it contains about notice periods, progressive discipline or any other features that it contains which give you due process rights. If there are no such rights contained within the agreement, there isn't anything you can do here to stop them from terminating you legally.