Roblox billing for Apple-download, that I didn't get

Roblox billed my son's debit card for (six) $4.99 charges listed as APPLE downloads. My son, in fact, never received any downloads. I spoke to APPLE support who said no purchases/downloads, at all, were made.

I sent various screen shots to Roblox support, but infuriatingly, did not acknowledge the problem, refused to explain the situation, refused to talk to me on the phone. Refused to let me speak to a supervisor. Finally, I just wrote them for the 6th time and they said they'd send the "issue" to billing to be looked at. They advised me in their email "not to dispute" my claim with my debit card company! Something really wrong going on on different levels. And not validating my concern, trying to figure the situation are just part of their terrible (in this case) consumer respect.