First of all, you must write letters to the landlord describing the problems. Telling the landlord verbally is not good enough. You need to put it in writing, deliver it and keep a copy. Include in the letter that these people are interfering with your quite enjoyment of your premises, and therefore the landlord will be in breach of the lease if he/it does not take action to remedy these problems. Multiple letters. If the problems are not fixed (either by landlord making these people be quiet or making them move), then you have to decide if you want to keep living there or not. Even if you have time left on your lease, you could move out provided that you have made a sufficient paper trial of letters to the landlord. However, before you break your lease, move out, and stop paying, you should consult a local lawyer on this landlord tenant issue. Good luck.
Answering a question through the AVVO forum does not create an attorney-client relationship, nor does any followup email. Do not send any confidential information as any right you have to confidentiality is waived (given up) when you post it through AVVO or send it by email. John Fason customarily does not agree to an attorney-client relationship unless there is a written contract describing the representation.
You need to be making complaints in writing. Get a paper trail going and then if the landlord does not cure the problem. See if you can get out of your lease. Refer to your lease to see what the language is for quiet enjoyment.