If there is something wrong with your sprinkler system, do not replace the whole system until you have called in experts. You may only need to repair a valve. Some contractors may come in and replace your entire sprinkler system and charge you more money than you needed to pay, sometimes three or four times as much. A company that will give you an estimate before any work is even started is one you are looking for. They can research the problem and will honestly tell you that you need to repair a valve instead or digging up your whole yard for nothing.
Look for someone that can come 24 hours a day and services any type of sprinkler system out there. Finding your problem is the key.