I am sorry to learn about this situation.
There is a series of escalating things you can do to deal with this situation. (I understand that you have already worked through some of this (such as contacting customer service), but I am including a full list as many customers have tried calling, but failed to follow up with written correspondence/confirmation). I also included steps that may not be applicable to your situation (such as filing a dispute with your credit card carrier), because I do not know how you paid your bill, and I do not want to omit a potential option for you.
None of these steps are required - you can pick and choose the ones you find are most suitable to your situation, but I find that working through these in a series helps provide you with a useful framework and can provide a systematic approach to dealing with a business.
With regards ***** ***** claim that they can "modify or withdraw" a promotion - this is true if it was only advertising, once you "accepted" their promotion when you agreed to have them install their service, they no longer can modify or withdraw the promotion - the "advertisement" is now accepted and a binding contract is formed. They cannot unilaterally change the terms on you (another term for this is consumer fraud or fraudulent advertising).
- *First: start with the company's customer service and dispute the claim. Keep your complaint in writing. If you speak to someone by phone, follow up promptly with a "confirmation letter" (see my note below).
- *Second: (you can do this at the same time), if you paid by credit card (not debit card) you can open a dispute with your credit card carrier (follow the instructions with your credit card company). (Some banks do allow for charge disputes on your debit card - but not all, the laws are not the same and debit card purchases do not have the same protections, if you paid by debit card, contact your bank and see if they do have dispute resolution remedies).
- *Third: open a dispute with the BBB. The BBB offers consumer dispute resolution that is fast, free to consumers, and is usually effective, they have no enforcement authority, but all BBB disputes result in a public report regarding resolution so businesses do respond to them. You can open a BBB dispute here: bbb.org/consumer-complaints/file-a-complaint/get-started
- *Fourth: if you believe that the company is acting fraudulently (not just charging high rates), you can report them to the state Attorney General. The AG's office does not prosecute individual claims (so they will not get your money back for you), but they will investigate and potentially take administrative and/or criminal action against the company.
- *Finally: you can file a small claims action against them for breach of contract. Small claims actions take approximately 3-8 months to go to trial. There is no guarantee of success in these disputes, but filing a small claims action does open an opportunity to negotiate a resolution (in addition to the above opportunities and can lead to mediation - many courts offer mediation programs for their small claims docket).
Confirmation letters: Keep written records of all communications - so if you speak to someone by phone, promptly send a follow up "confirmation letter" summarizing your conversation, who you spoke to, when, and any agreements you reached. Keep copies of your outgoing correspondence, as well as anything that you receive.
I wish you the best of luck with this dispute, and hopefully a speedy resolution.