If a customer spotted an error on your website and gave the brand a suggestion to improve the site, you would expect the brand to reply with a thank you.
Seriously, if Citibank isn't confident that its brand name can withstand one small complain about rendering issues about bank statements on their website on a Mac machine, it has wasted the millions of dollars spend on advertising and promoting its brand.
Plus, this is a suggestion, a thank you would have generated more social media goodwill.
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