The DFD transfer is unusual in that the new IP did
acquire the cases in Trust, however these were ring fenced and exist as a separate entity to the "live" cases.
If your case closed with DFD in 2016 you should contact email@example.com
. This address is still appropriate despite the recent takeover of Aperture by Jarvis - the IVA trust team still exists, at the moment.
John Fisher cases were transferred by court order to Richard Savage and Eleanor McKinnon in 2013/2014 and then on to Antoinette Thorpe in 2016 when Richard Savage left DFD, and then on to Elaine Masters at Aperture when DFD went under in 2017. But I digress! A clause in the court order for transfer of IP factored in the PPI clause I believe.
If you email the IVA Trusts address, they should still be able to locate your info. The general Aperture guys wouldn't have been able to locate a closed DFD case so it's not too surprising to me they couldn't locate it.
Is the CMC First Dispute Management by any chance?