Other members cannot tell you

Please do go to social media, no doubt you will get an accurate answer there from experts 

What were the terms of the gift card?

Did it say the amount had to be used all at once and remaining balance would be forfited ?

How do you know it was'nt this ' Roblox' site that drained you? certainly seems like a type of site that needs care when using 

When you check the balance and transaction record for the gift card, what does it show?