Customs clearance repeatedly 1-3 weeks - unacceptable!

I have a FedEx account and I ship 2-3 international parcels from the US and Germany every week. At least I used to. Everything was fine and customs clearance used to take 1-2 days, if it took a week that was extraordinarily long. However, since about 4 months the customs clearance times have gone up to as much as 3 weeks. I am actually waiting for a parcel for more than three weeks now. Nothing from my side has changed. I still ship exactly the same goods, there is always an invoice attached and all my details are on their system. Besides this being frustrating, it is also damaging to my business. I have now moved all my Germany shipments to DHL and even though DHL is significantly more expensive for US shipments, those I am also starting to move to DHL. Funny enough with DHL I do not have any customs issues, all their parcels clear very fast, I even get parcels from Germany in just 3 days, including customs clearance. I think they just have better relationships with customs and clearance agents that know what they are doing. I am very disappointed in FedEx and I wish you can just release my parcels that are being held, hostage. This is the very poorest customer service I have experienced in years with you! Another point I want to make, in the past 2 years, I have had THREE different reps from the PE office. They seem to stay for a few months, then they quit and it always took FedEx a minimum of 6 months to find a new one. In that time I'm left completely hanging with no contact person.