Is this a scam on ROBLOX???

I used to play Roblox with a friend, but he told me that at one point, he paid to get 100 Robux, I think, and he only received 3 or 5. He even showed me a screenshot and everything. Later, we started playing Bloxd, which is another great game but with lag. In Roblox, they always try to scam him with links and everything. Even Roblox once suddenly closed on its own. Is this normal?