Hello!
Firstly sorry for the delay in response. When it comes to items that disappear, you can make a support ticket (located under support) AS LONG as you have proof. Proof can be as a screenshot (f2) or through chat logs (e.g when you'd use logs - either a deal, inf chest disabling or through receiving announced slayer region items)
We do require some sort of proof so it is best if you start saving screenshots of new items that you receive. When you don't receive an item/if you don't receive a reward for something that you should've had, please make a ticket and provide as much information/proof as you can
^-^