You never get the sign up goodies as an existing customer.
FTTC normally has a minimum term of 18 months or so. If you are still within this I assume you would have to pay some kind of penalty if you go elsewhere.
If you do upgrade to Infinity 2 you will have the ability to get BT Sport "free" if that is of any value to you.
You may be able to negotiate "something" from them if you try, even if it is not directly tied to the excessive usage charge.
(Students are a pain - arent they. We have one as well
BT Infinity 2 - IP profile 77 / 20 - super fast!
Previously BE Unlimited - 21,000 Download 1,200 Upload but then moved house - 6,500 Down, 1Mb/s up - gutted!
Ex <n>ildram , been to SKY MAX - 15,225 Download