Being ****** by cell c

Cell c is charging me R51 extra on my router and when I phone they say it's subscriptions . How do I subscribe using a router? They don't have an answer ! I must get debited more than R50 for their poor security meausey, it can't be correct. My subscription is R300 but for the past months IAM being ****** by cell c debiting R351 . When I phone they say I make the subscription but how does one subscribe on a router?