Had a customer at a mechanic shop last week. Before signing for his package he started opening the box. I told him that he can't open packages until signing for it. He then gave me a sad story about how DHL shipped him a damaged part. I told him respectfully that I have to call my supervisor before boxes start opening without a signature. The supervisor gave me the go ahead to let the customer open boxes. After about 10 minutes of the cosignee b.s.ing me and attending his customers he finally opens the box. He takes his sweet time inspecting every single detail only to find it in perfect condition. I was understanding, patient, and willing to work with the customer. Everything seemed fine with the customer and I don't mind waiting in the a/c while getting paid by the hour. Next day my route is covered by another drive and I told him that to go ahead and let the customer open the box before signing. he also had to wait 10 minutes and also said that the customer did not like me, but gave no specific reason as to why. He also said he will stop shipping with UPS, again stating no specific reason as to why. 2 days later another part is ordered at the same shop. I locate another employee who always signs for the owners packages in hopes of getting a quick signature. The owner storms out of nowhere, gives me a dirty look and tells his employee not to sign. So again the same 10 minute waiting game for a part in perfect condition. He seems to me to be looking for something to complain about and give me a hard time. even though I'm doing it by the book and following orders. My supervisor suggested to DR MC MAN, but then quickly retracted that statement incase the part is actually damage. Any suggestions on dealing with customers that want to open packages in this case and in general?