Squirrels!!

[laughlast.livejournal.com]

I've never posted to a site like this before but it was recommended and I could use some help, so here I am.

I live in the top floor unit of a three-unit house and for the last few months, squirrels have been working their way into the walls and crawl spaces around my apartment (there is no attic space in the house - my apartment is directly under the roof so the squirrels are between the rooms of my apartment and the most slanted part of the roof, if that makes sense).  I have reported this to my landlords several times and they have been minimally responsive.  I have looked at my lease and there is nothing that speaks to their responsiveness to complaints and/or what constitutes disturbances about which I could withhold rent...etc.

In the last week or so, the squirrel activity has increased significantly and yesterday, one squirrel made it into my apartment...a thrilling experience a la National Lampoon's Christmas Vacation.  Obviously, I contacted my landlords immediately by phone and email and asked them to call but I only got an email several hours later.  One of them came to my apartment today while I was not home to take a look and I have not heard anything about what was found or what will be done.  In general, I have, as mentioned, found them sluggish to respond and rather rude and this squirrel issue has persisted for a few months.

So...I have two questions: 

1. Any suggestions of how to handle squirrel invasions? 
2. Does anyone have suggestions or know Somerville housing (rental) laws that might be relevant to this situation?  Can I withhold rent if the issue continues?

Any feedback is welcome!  Thanks so much.