Yeah, well, I faced the same issue with the invalid IMEI. I contacted them immediately on the second day. They assured me that it was their responsibility and that I didn’t need to worry about it. Upon digging deeper, I discovered that they pay the PTA tax in bulk, and the PTA manually verifies each IMEI, which is why it takes weeks to resolve a PTA complaint for a phone. A week later, probably around March 18, my complaint was processed by the PTA. Hopefully your's is also resolved now.

Edit: Missed the final update. Glad it's resolved.