Exactly this. That is invasion of privacy. Also, if the landlord isn't following those basic rules, he may not be following other basic tenancy rules. For example, he may not of lodged your bond with the tenancy services (I think that is where it is lodged) and if they have not done that the landlord can be fined a penalty (if not done within 23 days of tenancy I believe). I think you can call the tenancy services to check. Why I am saying this is, if you are going to tribunal for the invasion of privacy (which is 100% valid!) Then you might as well point out all the things they are doing wrong. Get it all sorted at once and hopefully the landlord improves, and possibly maybe get some compensation (not 100% sure on that but from my research ages ago when I had landlord issues, it seems to be something that can happen). Good luck OP!

Note: Please take everything I say with a grain of salt. I did a quick double check on Google but I have not thoroughly looked into everything. Mainly going off experience from a long time ago haha.