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This type of service may fall under your state's "cooling off" laws (although I am somewhat worried that it may not - most of these types of services are deemed for "personal use" and therefore exempted from this otherwise "in-home purchase" (see: http://www.consumer.ftc.gov/articles/0176-protections-home-purchases-cooling-rule
You can try filing a dispute with the BBB (the BBB offers free dispute resolution
for consumers, it is fast, and while they do not have enforcement authority, filing a claim will not preclude you from pursuing other options). You can file a BBB claim here: https://www.bbb.org/consumer-complaints/file-a-complaint/get-started
You can also file a complaint with your Attorney General's Consumer Protection division, but based on what you have posted, the provider's service fees are high, but it does not appear that they hid or concealed any of their fees.
You can try suing them in small claims court, but again, the terms of their agreement are high, but they do not appear to be fraudulent. Your wife's medical condition does not constitute a barrier to her ability to contract (mental impairments only act as a defense to contract claims when the other party knows, or reasonably should have known, that the party they were contracting with lacked capacity to enter into the contract - was unable to comprehend the terms of the agreement - which is a fairly high standard to meet).
Short of filing a lawsuit, you can try to mediate the dispute with them - contact your local bar association and request referrals to mediators, a third party neutral can often help you reach a mutually agreeable resolution. Use the bar association's referrals to contact a mediator or two, the mediator will then contact the other party to set up a mediation
session, and you can go from there - hopefully resulting in a formal or written settlement agreement, and save yourself the time and expense of litigation.