1500gv

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hello all new to the chevy forum! i have a 2015 silverado 1500 rally 2 edition got it brand new as a lease i have 27k miles. The truck would not start the other day and then it struggled to start after multiple tries the navigation screen looked out of wack many buttons were missing my windows would not go down and my message screen said service theft deterrent system. I take it to the service dpt at beck chevrolet in yonkers ny where i purchased the truck they tell me its the key use your other key and sent me home. I used other key and the problem was will there. I went back today and they have no time to look into it due to high volume of customers and no loaners if i did want to leave the truck. With this service issue ,10 months left on this lease and poor customer service at my local chevy dealer id really hate for this situation to result in no longer leasing from chevrolet or gm financial... any advice