We're awfully sorry for the inconvenience caused.
有时可以再加一句:
We appreciate your understanding in this regard.
11月17日是November 17th,通常写Nov 17就可以了
对此造成的不便,我们感到十分的抱歉
We are so sorry for the inconveience we have caused.
yes, "November 17th" is right.
Regarding this creates inconvenient, we feel the extremely regret
To make it be trouble,I\'m very sorry for that!
We are so sorry for the trouble caused!