Package held up at JIMC customs

I am waiting for my package to arrive since March. The Post Office tracking website is very slow and I struggle to get a day where I can track it. Phoning the 0860 hotline was very helpful. Now I received in the post a slip where JIMC requires an invoice. Again the Post Office 0860 help line told me what to do and gave me an email address. Firstly, Why is there not an email address on the slip? I have an option of 4 numbers to contact JIMC, but NO ONE answers these numbers. They wasted more than an hour of my employer and my time, due to no one answering. I can't phone the whole day on my employers expense!!! What does a phone number help if no one takes your call?!