Engine Clicking And Tapping Noises problems of the 2012 Buick Enclave

We purchased a �certified pre-owned� 2012 Buick Enclave from royal Buick of sussex new jersey in February of 2017. The car shut off on Friday January 11th. It was towed to rossi where we have been taken it for almost two years of ongoing maintenance, both scheduled and non, and have spent over $10k in the last year alone, on service that did not resolve the clicking sound coming from the engine. Earlier that day I had made the earliest appointment available which was 10 days later, on the 21st. After breaking down, we went to their showroom that following Saturday and were seen by charlie. He wrote up a very reasonable deal for $1k down with many incentives including one for me being a volunteer emt. Matt the sales manager came back and told us that my wife's credit score was not what we had claimed and qualified for a tier two instead of a tier one which now required a $6k down payment. We checked my wife's credit score on experian before we left rossi and got the same score we had given matt originally, which we showed him and to which he responded "we use a different system". We decided to keep the Enclave and repair it. The battery, solenoid and valves were repaired before the 21st and we were told that we could pick-up the car after it was test driven by the technician. We did not hear back from rossi service so we called and were told that when test driving the vehicle after the most recent repairs - the technician heard a clicking sound coming from the engine. Wow! that sounded very familiar as this was the complaint we had often submitted to rossi in the past and that we suspected prompted expensive and unrelated repairs. This time however they told us they would need to diagnose the engine, so the next day they called us and told us, the car, with just under 103k miles - �needs a new engine�. No further explanation was offered except a quote of $6k.