電話が殺到しておりまして、お待ちいただいて申し訳ございません。

Thank you for being patient as we respond to the high volume of calls.

電話(でんわ)が殺到(さっとう)しておりまして、お待(ま)ちいただいて申(もう)し訳(わけ)ございません。

Denwa ga sattōshiteorimashite, omachiitadaite mōshiwake gozaimasen.

電話 (でんわ)

telephone call; phone call; telephone (device); phone

が (が)

indicates sentence subject (occasionally object); indicates possessive (esp. in literary expressions); but; however; still; and

殺到 (さっとう)

rush; flood

申し訳 (もうしわけ)

apology; excuse

御座る (ござる)

to be

Reading: デン

Meaning: electricity

Readings: ワ、はな.す、はなし

Meanings: tale, talk

Readings: サツ、サイ、セツ、ころ.す、 -ごろ.し、そ.ぐ

Meanings: kill, murder, butcher, slice off, split, diminish, reduce, spoil

Readings: トウ、いた.る

Meanings: arrival, proceed, reach, attain, result in

Readings: タイ、ま.つ、 -ま.ち

Meanings: wait, depend on

Readings: シン、もう.す、もう.し-、さる

Meanings: have the honor to, sign of the monkey, 3-5PM, ninth sign of Chinese zodiac

Readings: ヤク、わけ

Meanings: translate, reason, circumstance, case