The buyer's remorse law doesn't apply in your case since it wasn't the result of a door to door sale and isn't one of the other categories. However, the FTC does have what is known as a "cooling off rule" which may help. I've never seen anyone actually use the rule in a case but it does exist and I will give you a link to it at the end of this post.
Your problem is that they've told you "no" and they have it marked on their computers now, so you can demand they cancel, write them letters, call, etc. and they're not going to change their decision. What you have to do is get someone else involved that they are more afraid of. These companies know that out of a hundred people that threaten a lawsuit against them, only one or two will move forward, and most if them will try to do it themselves, will mess it up, and the company can get the lawsuit dismissed. So if they just "play the odds" they make more money.
What I'd suggest is to file a complaint with the FTC at www.ftc.gov, with your state's Attorney General at https://www.attorneygeneral.gov/Complaints/Consumer_Complaint_Form/
and then hire a local lawyer to write a letter to DISH for you. The lawyer isn't going to charge much, if anything, to write the letter and that is more likely to get a favorable response than anything else. If they tell him no, then the only things you can do are 1) wait to see what the FTC and the AG say, 2) go ahead and sue DISH, or 3) wait for DISH to sue you and then countersue them.
DISH isn't going to do anything as long as you keep paying them, but discuss the options with the attorney and he'll address those in the letter with DISH as well.
AS I said earlier. the PA buyer's remorse law doesn't cover all contracts in PA and, more importantly, it doesn't cover yours. Many people believe it applies any time a purchase is made, but that's just incorrect.
You can see the PA statute, and that what I am telling you is correct, at: http://www.legis.state.pa.us/cfdocs/legis/LI/uconsCheck.cfm?txtType=HTM&yr=1968&sessInd=0&smthLwInd=0&act=387&chpt=0&sctn=7&subsctn=0
The page with the info about the FTC Cooling Off period is at: https://www.consumer.ftc.gov/articles/0176-buyers-remorse-when-ftcs-cooling-rule-may-help
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