A few days ago, I accidentally hit "exchange" when I meant to "store" an expensive piece of gear. I didn't realize this for several minutes, and the buyback window had already passed. FDev were unable to help, but provided some insight in a later response to my support ticket...
Thank you for contacting us at Frontier and I apologise for the delay in response time, we are currently in a high traffic period meaning that unfortunately, we may take longer than our targeted 24-hour response.
Having taken a look into our systems backend logs unfortunately we do not have any backups for this module! This is often the case when selling a module as when the module is sold the instance of the object holding the data regarding the module is deleted and exchanged for the credit equivalency, sometimes we are able to restore the module if a death has occurred (as during death a whole ship with modules included backup is taken).
I’m sorry I am unable to assist further in regards to this matter, however, if you have any further questions please do not hesitate to ask as we are always happy to help! :)
Fly Safe Commander .
Elite Dangerous Customer Support Wing
TLDR: Be careful when you store modules, or retrieve them from storage!