I had a very similar experience, only worse.  I needed to upgrade my phone and my son needed a phone, so I upgraded to the iPhone 5s with a new 2 year contract.  They told me about the "free tablet" and I said I didn't want it.  They said, "But it's free."  They did tell me about the return policy, but didn't tell me about the $10/month charge.  They also told me that since my son's phone is an old one that I would only have to pay $15/month for it instead of the usual $40.  I didn't care about the restocking fee on the tablet because I was not planning on returning it.  After all, it was free and if I didn't like it, I figured I could sell it on eBay or give it to a friend. 

When I got the bill, I was surprised by the $10/month jump in my cell phone plan and went to complain about it and they said that I was locked into it for 2 years and that they would let me return it this one time since it was past the 14 day return policy.  I told them that I didn't know about the $10/month access fee until my bill came which was why I didn't bring it back in less than 14 days and they felt like they were accommodating me by letting me return it.... for a $70+tax restocking fee.  They also said that the $15/month fee for my son's phone was only if I had the 10 gig data plan and I only had the 4 gig plan, so I have to pay $30/month.  I told them that it was totally unacceptable and left.

I went home and called corporate and gave them the full story, filed a complaint against the store and they gave me a whopping $15 off my bill for one time only.  I asked how much it was to cancel my entire contract and they said $850.  I packed up the tablet and took it back to the store and had to sign the "I agree to the terms of this return".  I verbally told them that I was signing it only because I had to, but that I did not agree to the terms, but was forced to by Verizon's return policy.  It was either return it for $70 or pay $240 over the next 2 years in monthly charges for the "free tablet".

I have been with Verizon since before Verizon was Verizon.  I have been with the same cell company for 20 years and they repay my loyalty by screwing me over.  At this point I am contemplating giving them $850 to buy out my contract and taking my business elsewhere.  At least they won't get the $5,520 that I would spend with them over the next 2 years while waiting for my iPhone 5s contract to run out.

I am waiting to see if customer service calls me back to make things right.  I spoke with them yesterday to lodge the complaint.  If they don't fix it, I'm gone.