I see it is a shared accomodation.
You have to make a complaint to the agent in writing about the conduct of the tenant. Ask them to do something about her constant breaches on the lease.
The more details you can give the better.
If you have sent her emails to request she comply with the rules these can be used as evidence .
If the agent then fails to act you can then complain about the agent to Magistrates court for failing to manage the property and breaching the rule of you being able to have your quiet enjoyment of the premises.
If the tenant that is the problem is subleasing form one of you then you can issue her with a notice to vacate under the law and if she refuses then list the matter with the Magistrates Court.
Here is a link that sets out the situation and look at paragraph 2
Here is the page where you can download the Notice.
This only applies if she is subleasing from one of you who has the main lease.
These are your only options.
If you wish to have a phone call to discuss this in more detail please elect a call or I can send you a request.
I hope this makes sense and is of assistance. If you have found my answer to be helpful, please rate me five stars so I can get paid for my services to you. You rating my work 5 stars allows me to continue to provide a service to those who require it.
I am happy for you to ask further questions on anything you wish more detail on.
Let me know if I have answered your question today.