Apple has started issuing refunds to iPhone 4 users who purchased Bumper cases from the online Apple Store. According to a customer email from the Apple Store posted on Mac Rumors’ forums, Apple is refunding both the retail price and any shipping or VAT charges that might have been applied to the order, noting that if the customer paid via credit card, it may take 3-5 days for the refunds to reach his/her account. Apple announced last Friday…