Sharon
AA have changed equipment for this route quite a lot recently, to fly a single-cabin plane. AFAIK, you should be able to have BA/AA move you to an alternative flight on or around the same day that has AA "First" for no charge, but I would note two things.
Firstly I think you should have been charged 13,500 miles as AA have no biz class, only "First", and BA usually charge accordingly.
Secondly it's a very short flight and AA domestic short-hop First is pretty mediocre. It's not worth burning the extra miles really, especially if you or another traveller have any OneWorld status to allow you to select AA's Main Cabin Extra seats with a bit more legroom, get early boarding etc.
As an aside, if you need to rebook, then depending on where you are in NY and are going in Toronto, Porter is a really good choice, flying from Newark to Toronto's very convenient downtown Billy Bishop airport, and I think they have a sale on.