Bought 380 Robux on Hesao.com but Only Got 279

I purchased 380 Robux through Hesao.com, but only 279 Robux were added to my account. I made the payment using my debit card for $4. Despite completing the purchase, I received fewer Robux than I paid for.
I am requesting a full refund of the $4 I paid to Hesao.com. I would like the short-delivery issue to be investigated and resolved as soon as possible, with my money returned to my account promptly.