Thanks Alt and Tacit for your replies, which are always good.
Since the likelihood of them seeing a thread in the Lounge on a computer forum is infinitesimally small, I might as well say who they are: Bayer, a global corporation (sales in one quarter year over €10 billions).
All our customer are on one-year contracts. Standard procedure is to invite customers to renew about eight weeks before contracts end. The response to my posted invoice was a phone call telling me which purchase order number to put on that invoice, and to email it to a certain address. (I did this earlier in the year for another Bayer customer and it all worked as it should).
This time the PO-number certified invoice was rejected (as above). I emailed the lady who had telephoned me and reported this. She agitatedly said that she was new at the job and didn't know what to do next. My response was that she should make enquiries at her end, as I had done as instructed.
24 hours later having heard nothing further, I emailed a fresh PDF, which was also rejected. I copied the rejection email to her, and to the person named on the invoice (her boss?).
A further 24 hours later, still no response (this all in normal business hours), so I posted here in case anyone could figure out their "error message".
Yes I have checked all junk email boxes at this end.......
What I have decided to do, is to waste no further time on one order from one customer (out of thousands) and let that contract expire. When he wakes up and realises that our product is no longer arriving, he will contact me directly or ask someone so to do. Then I will tell them that their computer systems repeatedly reject my invoice which was requested; and that it is to be hoped that not many of their other worldwide suppliers suffer similar frustrations in billing them!
