I got scammed by an agent

I got a higher bill in January, I thought it must be a mistake and it gets corrected next month. It didn't happened so I wrote to the chat, and one agent told me I have some limited data so I'm paying extra because I used some over the limit data. He proposed me some $70 deal (from current $25) which I declined. So I ended up speaking with Akshay, another agent, from a "Dedicated Team" to help me with another astonishing offer. I was asked to accept the same $70 offer for unlimited data, which I declined asking if they can match the $30 service cost from Verizon internet service. The agent assured me they can, even though in the proposal I had to accept was a higher price the agent convinced me "it will be $30  as it will be adjusted and lowered" when I asked if $30 will be the final price on the bill(the quoted text is from the chat transcript, exactly what the agent wrote). But the surprise came with the bill, which proved to be about $70 because it's $50 monthly plus some extra form the previous month, since when it's supposed I'm using the upgraded internet - but the matter of fact nothing changed except the bill. I tried to speak with another agent to get the $30 service it was promised or at least to get back the $25 limited service I had in the beginning and after I was bouncing between 4 or 5 agents somebody told me the best he can is to give me a $60 bill service, even though I have the chat transcript where I was assured I'm getting a $30 unlimited service.

This looks to me like a scam schema, I was ok if the agent would have told me they can't offer a so low price as $30 per unlimited service, instead tricked me to get an upgrade for a price I didn't agree and I repeatedly told him so. Also, there is no possibility for an end user to get access to the old chat conversation, some chat conversation like the negotiated prices is removed, the information about the complete service details (like data limit) is not available in the customer account, the customer portal has poor response, probably an overloaded database and these changes in the service are nowhere to be found, except the higher bill.