SFR STick
I am just north of Poitiers (79). Have been to Vendee and Bordeaux where it worked really well (for a stick on a laptop). By the way, instead of plugging straight into a USB port I used the cable connector supplied - it makes all the difference, do not understand why!
The top up cost is Euros 9 for 48 hours and progresses for more hours. Have a look on SFR.fr.
It has sorted my connection problem when on the move.
Happy travelling.
Kevin