No trucks availability

I don't get "the 3 Fairs". Is that a special name for something? I ask because you capitalized 'fairs'.

I regret to inform you that we are not able to offer you our services on the occasion of the three fairs because no trucks are available on those dates.

If you are absolutely wedded to the "due to" phrasing, you'll have to use a somewhat cumbersome phrasi

Hi CJ,thank you. I don´t know why when I am in the office and use a different PC I am unable to quote and my sentences have no space between them...Anyway, I mean 3 different kind of fairs (I don´t know why I capitalized "fairs"). I like your corrections but I don´t know why I prefer using "due to the fact" maybe I like complicating sentences :-)) One question regarding "on the occasion" is reall

Pamela81I dön´t know why I prefer using "due to the fact"

Well it's not wrong, and it occurs a lot in "business lingo", so you may have developed a preference for it that way. There are a few style manuals that recommend against it nevertheless.

Yes, I'm afraid "in the occasion" is really wrong, at least to my ear. The only phrase I'm familiar with

Thank you, very clear CJ.In Italian I would say: "In occasione di" so it sounds to me more natural to say "in the occasion of" but I´ll learn to say "on the occasion of" :-) Thank you

Hi Pam,
I see you already had help from CJ. But just an extra two cents If you must use the "due to" phrasing, this may be an option for you:
It is our regret to inform you that due to the high demands of trucks during the fairs, we are unable to provide trucking service to you on the dates as requested.

Hi Disumexpress, thank you, I like your option as well :-) Regards