Anyone know anything re: legal renting issues? :/ (Stockholm)

Hi everyone -

I have a somewhat odd question about legal renting sublet contracts here in Sweden.

So here's the situation: My boyfriend and I have been living in the apartment of an older man in downtown Stockholm since August of last year. When we signed the contract, we asked him if he had the legal right to sublet to us, and he said he did. However, after signing the contract he mentioned to us that he did not want us using this address for any mail delivery until after November........this is shady, right? I have read that landlords only allow the first-hand contract holder to sublet for certain periods of time before they are obligated to actually reside in the premises themselves, but I have a hard time verifying that when I don't speak Swedish. :/ My second question would be that if indeed that is a law, and it sounds like he would be breaking it....who would stand to be punished if we were to tell the owner of the building? Us, him, or both of us? Can we or he be legally evicted in those circumstances? Finally, is there a branch of the housing or legal system that has people that would be able to answer these questions for us even though we don't have a personnummer? (Long story, we're 100% legal but only here 11 months so no PN)

I am only investigating this now because in the 7 months we have lived here we have amassed a list of grievances against this disgusting and immature person that would take me hours to recount, which no worries I am not about to do here; however we are now trying to gather information regarding him and our situation in the case that we may need to go to court with him over money issues. Any help you can give us or directions you can point us in is so so greatly appreciated, tack så mycket för hjälpen!

Jen