Business English: Customer Service Communication

Which sentence is more polite and professional?

There is a mistake in your form. Could you please check it again?

"Thank you for your patience. We are currently ______ the issue."

"We apologise for the inconvenience and we are ______ the problem."

Choose the most professional response to a complaint.

You should have read the instructions first.

I understand your concern and I will help you resolve it.

It's not our fault, you should call this number in stead. 

You must calm down, if not I can't help. 