Worst first impression of mobile service EVER

I called in to discuss when I would pay my internet bill. The gentleman Ken had told me all these promotions that I would receive if I moved over by mobile service from T-Mobile. I had been with T-mobile for 16 years. I was always cautious to switch bc it always seemed too good to be true and I was happy with T-Mobile. Well I should have known. I told Ken I wouldn't want to transfer until I paid off my sons tablet bc T-Mobile would want be to pay it in full on the final bill and I couldn't afford that, and I also didn't want to owe one company a tablet and the other for my cell phone. After being told Xfinity would pay off the tablet, I would receive $200 in gift cards for bringing over my phone and my wifi bill would go down $40 a month making it $18. Then it could go down even lower another $10 if I did autopay with my checking account instead of the debit card it was already on autopay with. He called T-Mobile on a 3 way call. Told them to notate my account that Xfinity would be paying the tablet, all I had to do was fill out a form. I transferred my services. I even told 2 family members that they should switch bc how much they could save. Well 2 days later I called back to find out what form to fill out for the tablet and what I needed to do to receive the gift cards. I was told there was no promotion where they paid off the tablets but that I would be receiving $200 in gift cards by 4-6 weeks and in 14 weeks there would be another $100 sent to me. I was disappointed ask for a manager to review the recorded call and see that I was not "misunderstood" like I was told but Ken had said all these things I was told. That gentleman gave me the form to fill out for the cards though. I started to fill out the form, only to find out that the gift cards were only for devices with a balance, I had told every single one I spoke to that the phone was paid for, they never said it was only for financed phones to help pay the balance of. So I called back to ask how to fill out the form since the bill the form wanted wouldn't have a balance on it. I was transferred to a promotional specialist, she then said no, tablets and paid are phone are covered in the promotion and tried to walk me through how to fill out the form for both. Once she read over the form, she placed me on hold to confirm with management. She came back and said that neither promotions applied to me and that I would only be receiving $100 in a gift card 14 weeks after activation. I then asked about the $40 discount of my wifi bill at least. I was then told there was no such thing and the $40 discount was bc I was getting a free phone line valued at $40 for a yr. I'm furious, I told the family members about my experience and how in disbelief I am that a corporation could be this unprofessional and to lie to get a sale. Also no manager ever called me after reviewing the recorded call, I was also told, managers wouldn't compensate me in anyway it would just be told to be a misunderstanding. I have since tried to cancel the tablet plan before the 7 days bc they start billing me for a tablet I never activated and it’s just a run around. I wish I ever did this