Installment plan billing bait and switch

App said I was eligible for installments on my bill of only $200. Offer was I pay $50 in good faith and get the rest lowered to $12.97 over next 12 months. Paid the $50 and then didn't receive the installment plan. I have screen shots, I tried hitting support up and was met with it didn't go through on their end so they turned my Internet off and then I got it turned back on(without my approval) and then same thing happened, so I incured two reactivation fees on top of what I owed. Then an agent signed me up for a payment arrangement without my approval just to get my services turned back on. I talked to someone about it just trying to get back to the original installment payments and they said no way it could happen. So they signed me up for a payment arrangement. And now I spent three hours chatting because phones don't work apparently, and got pressured into a 24month contract being told it was the only way to keep my services on and two week from now I can change it. No explanations given when I asked and the plan was for more than my current plan. I just want those installments I was promised at the beginning(I have screen shots) and also would like to change my plan to something more manageable, because why would you not want me to be able to pay this off? Doesn't make any sense and is very predatory.