The only way that you can get around that is to purchase a phone for the full price, not contract price and then apply it to your plan or buy a used phone from ebay and apply it to your plan. You want a new contract phone you will get a new contract. I have owned my iphone 4 since August and have used almost 1.5GB since I owned the phone, I never hit the 2GB monthly limit (I am always on wifi, I leave the data off unless I am out and about).
From what I was told from a verizon engineer when I was setting up a township pd on the verizon network (they needed a verizon engineer out due to constant dropping and data stream), he stated that although verizon leases their towers out to other companies, they don't lease all of their towers out.
Out of all providers (sprint, att, tmobile), when hurricane sandy hit only verizon wireless service was stable. All other companies had 0 capability, no phone calling no texting, no data, nothing. Texts would take days to reach the phone, it was a mess if you weren't on verizon (my verizon phone was the only one working in the department, everyone else had sprint/att/etc)...company since switched entirely to verizon.