They’re a not-for-profit, AFAIK they sell the bikes just to fund the efforts to keep serviceable bikes out of landfill and give folks who’re short of a skill the chance to gain spannering work experience and qualifications. Also, AFAIK they don’t buy bikes, they just recondition donated wrecks.
…Maybe your theif realised the bike wasn’t worth much and dumped it, someone found it and gave it to a good cause?
Who did you speak to there? Not everyone will necessarily have all the info or be in a sufficient position of authority to feel like they can sort this out to both your satisfaction…
Edit: Yep, Ninja, Ben is a top bloke and the guy to speak to at CycleRecycle to get anything done! – I can’t believe he’d not get this resolved.