huge bills your mistake

i opened a contract in december 2015 they gave me the lg gpad they said it can make calls i found out it cant they said they will cancel that contract i made a new contract for the lg g4 beat end of december they deducted R900 cell c said i must reverse thst money only pay the R505 that i must pay after few days cell c send me a messae saying i ow then R395 the cell c power station in president hyper said i must ignore those messages it will be sortet out they want to black list me they caceled my service but its cell c's mistake its the 20th of January nothing has been done i want this fixed this is the worst service if its not sorted out before my dedaction legal actions will be taking place i have prove of all messages ect