Firstly can you downgrade your current plan (maybe cite financial difficulties) as that would be cheaper to downgrade to the lowest package possible and sell the phone to cover the remain un-used bills, then the world is your oyster as all current providers seem to offer better deals.
I recommend most android phones, avoid Sony Ericsson they haven't made a good phone for years, I like my HTC phones even with the poor battery life (which smartphones don't have poor battery performance)
I would always strongly recommend buy direct from the network website or over the phone with the network, having once worked for a network all the 3rd party companies cannot be trusted, from lieing about what you are getting to selling your details i've seen and heard it all even he big guns do it. The advantage of a telephone/internet sale from the networks direct is you have 7 days to try your new phone and service out if you don't like it notify them within these 7 days and you can return it and either choose a different phone or cancel the agreement all together.
Hastily written apologies on the quality.