Does Cox Throttle Speeds?

I was noticing that for around several weeks my download speed was hovering around 37Mbps instead of the 50 that I was paying for.

I contacted a representative from the site and he told me that Cox was sending all 50Mbps and that I was simply not receiving it. He suggested I reset my modem as that could be the problem so I did. Resetting the modem didn't help so I reset the router afterwards. That also didn't help so I contacted customer support again.

I told the second representative the same thing as I told the first one, that my speeds were not where they should be. He then told me that because I was exceeding the data plan for my service that Cox was throttling my speeds. I looked at the Data Plan FAQs and it said specifically that Cox does not throttle speeds. Since the FAQ was updated on November 3rd, has Cox started to throttle speeds? I even asked him when Cox started to do this but he stated that he didn't know. 

Can anyone show me where it states that Cox now throttles speed or if this guy was lying to me?