https://blockchain.info/tx/cf9c6581f7fca16241d2ee18cb797b723339cb24a75a822f4004e65f94e47f06
Double spent transactions will be tagged as "Double spent" like this x spent the same outputs as y something from block explorers so you can easily identify it and as you can see its not. The miner fee included is just too low making the transaction stucked so honestly he doesn't have the right to call you a scammer as he included a low fee moreover unconfirmed transactions can't be trusted so you have every reason not to send the riot points until confirmation comes.
With that fee i doubt it will ever get confirmed so I quequed your transaction on antpool. It should be confirmed within a few hours.