MULTIPLEX is a relatively small company! Somethimes I think they have never expected such a high number of enquiries. So there might sometimes be too much work for the poor guy or lady who has to answer, give on or do what ever with all the questions.
It is easy for me to say "just call them up" because I live in Germany. For those from abroad it often is quite difficult to do so.
On the other hand the MULTIPLEX-team is almost in any case eager to help as good as they can - mostly to the customers satisfaction.
So keep an trying!