Inspector reported non-compliance with procedures concerning quarantine of an ELAC following vendor repair. The unit was released from quarantine; subsequently installed and then failed; resulting in returning it to the vendor.

Narrative

Receiving Inspection on Elevator/Aileron (ELAC Computer) *AD2018-0007R1 2793-01014*; Repaired by Vendor on order #XXXXXXX. Rejected; placed in Quarantine discrepancy area due to Vendor XXXX-X has incorrect part# as per ECRA XXXX-XXXXX Rev. X compliance; ref. Labeling instructions Page X and Page YY of ECRA (Also see page 11). Unit arrived with Labeling attached; but MFG P/N was not crossed out (as required per ECRA) from previous Labeling.Sent out Company P/N per App transaction and OAL Original order sheet showing MFG P/N 3945129100U1; received MFG P/N 3945129100 per block-X same MFG S/N for both (Means it is the same Unit).When you research MFG P/N 3945129100 in App transaction it says do not buy; Suffix after the part number indicates Software was downloaded specific to Company. The Vendor had no information stating the L101 download software was completed; but the tear down sheet did. It is an AD note; regardless I want 100% compliance without any doubt.Unit stayed in the Discrepancy area for approximately 5 weeks without any resolution until it became Hot AOG; email correspondence sent through company emails to Vendor without any resolution and then to another Inspector bypassing the resolution process trying to find another Inspector to make it Serviceable telling the Inspector to make Serviceable by email requesting Unit to be sent to Shop. During this time Order XXXXXXX was changed reflecting the MFG P/N removing Company P/N !! (Obviously to push the part through).This is ongoing problem at ZZZ removing parts out of quarantine without resolution; Avionics Shop Analyst; Business Services is constantly requesting units to bent sent to the shop before resolution is answered; Completed. Eventually after the part was again dumped off to me in my persistence; but part was not finalized through (Inspection) and was eventually completed by Avionics Shop.This ELAC Unit has chronic history of failure and failed again in service according [to] App history transaction and is back at the Vendor again.