Negligence

I have waited 5 months for my necklace to be repaired and upon it being repaired, the pendant was missing. It turns out the necklace belonged to a different customer with the same initals and surname as me. This simply means that they do not check if the job numbers correspond with the customers reciept. So how many other customers has recieved the incorrect goods? No response from area manager and there is no store manager. The store manager from American Swiss assisted me.