Charged for a Trouble Call

We were having issues with our internet and we called and had someone out to look at it.  The router wasn't working so he replaced it but we were charged a Trouble Call Fee of $99.95??  It wasn't something that we did on our end, it was that the router quit working.  Can someone please contact me so that we can get this reversed, as we don't feel that we should be charged - when we pay each month to have a working router and clearly this wasn't the case.