Hey there, and welcome to our Support Community. I'm so sorry that we're not greeting you with a better experience to report!
The issue you're explaining here is definitely not OK. We should be up front about any purchases placed on an installment plan, and honestly since the EIP is a legally binding financing agreement, we should gain a signature every time we start an installment plan -- whether for accessories or devices. When you worked with our Care team over the phone, were we able to file an incident report for you? This is something an internal team can do to make sure that feedback goes directly to the team in question. It sounds like the retail supervisor of the store where this took place is reviewing the matter as well, which is good. I'm not sure if you're outside of the standard buyer's remorse timeline for returning these items, but given the misunderstanding that's certainly something I think is worth checking into.
While I know based on your post that you've already contacted our Care team over the phone and the store in question, if you're looking for another avenue to reach out regarding this situation we highly recommend our T-Force team. They're our customer support teams over social media, on Twitter and Facebook. In those channels we have a secure platform for account access and can verify your account and take a closer look at this. T-Force can also file the type of report I mentioned previously.
We appreciate the time you've taken to post about this experience here, and I am going to send a private message your way to make sure we have all of the details we need to forward the general feedback to our sales team, but for help with your specific account, please Contact Us!