Do I need a suit for a business casual interview?

I got a call back from a bank job I applied for, and the online interview is coming up in two days. The hiring manager stated the dress code is business casual. I'd be working a mostly online/technical assistance position. I have a nice dress shirt, slacks, tie, and dress shoes I was planning on wearing for it.

When I told my friend about it, he said it's not enough, and I should be looking at next-day shipping a suit jack or blazer.

I feel like an idiot. This would be an amazing job for me, but getting anything now to wear would reallt entail me rushing to the only overpriced tailor in town and paying hundreds for a suit or blazer that I wouldn't have time to get fitted. What should I do?

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