Just a tip from a customer service pro: Don't use "I'm sorry." Instead, use "I apologise," this accomplishes the same end while taking the personal subtext out.

Just a tip from a customer service pro: Don't use "I'm sorry." Instead, use "I apologise," this accomplishes the same end while taking the personal subtext out. And, as the commenter above mentions, it should be followed up with "what can we do to fix it"!