A man described by the information regulator as a vexatious applicant is once again tying up resources and potentially delaying a landmark case by inserting himself into proceedings over the multi-billion dollar fees for no service scandal.

Phillip Charles Sweeney has filed an affidavit as an interested person in the matter between the Australian Securities and Investments Commissioner and NAB – the first major piece of litigation launched by the corporate regulator against a bank for charging fees it had no entitlement to.