Someone said :
Not quite computer but techie nonetheless.
I went to the phone store I have my bill pay account with, and upgraded my mobile broadband. All I wanted was to number of bits I get each month, but apparently that comes with a new dongle to connect me to the rest of the world, "free". Do I need a new dongle?
Depends on your provider.
If it is some kind of 4G broadband, then the dongle is probably there to allow you to connect wirelessly to the internet, when you are not home.
If it is a Vodafone dongle, then it is a "4G mobile broadband", which you can plug in your router to get wireless access (instead of plunging a phone line), or which you can take with you on-the-go to connect to 4G mobile broadband anywhere (but then home might be internetless.
Or it could be a combo of both, where the dongle is an extra to get wireless on the go, while your router may have a SIM card to achieve the same at home.
The catch may be that on the 4G mobile broadband, you are not on an "unlimited" contract. So your original question remains: what broadband allowance do you have on your contract. You may get more answers from your online account than from a spotty store "genius".