Hi Donna,
I have had a pay as you go dongle with vodaphone which was an absolute nightmare. When you go and top up your credit if the shop does not activate it properly the credit runs out really quick. The shop will not take responsibility and i have had endless heated discussions over the phone with Vodafone which actually charged my a fortune on my mobile.
I did get to the point, after it costing around 150 euros a month, that i need to ditch this.
There is a number of dongles on the market but the thing you have to do is check the signal for your main area of operation. i.e your home address.
After checking the signals for them all ironically vodafone came out best for where i live.
So,,,,,, I checked the cost of the contracts.
If you purchase the dongle with a seperate fee you can get a contract that you can cancel at any time around 35 euros from The carphone people in DOs Maris.
If you get a free dongle then unfortunatly you are tied to an 18 month contract.
Soz