You are still engaged with your current mobile operator in France because you have a 12 or 24 month commitment but you still want to change operator, to go to Free Mobile for example?
Be aware that you will have to pay a termination fee.
Note that thanks to the Châtel law , if you were subject to a 24-month (2-year) commitment, you will only have to pay a quarter of the sums remaining due after the 12th month.
If your commitment was only for 12 months or if you terminate before the 12th month of your 24-month commitment, you will have to pay all amounts due until the 12th month.
You have a package of 30 € over 2 years , you cancel after a year and a half , so you have a quarter of the last 6 months to pay:
-> 6 months * 30 € / 4 = 45 € to be reimbursed to your old operator.
You have a package of 30 € over 2 years , you cancel after 10 months , you have 2 months full price to pay + a quarter of the 12 months of the second year:
-> 2 * 30 + (12 * 30/4) = 60 € + 90 € = 150 € to be reimbursed to your old operator .
NB: To change operator, you will need to know your RIO code (Operator Identity Statement) .