Ground 10 only.

I have just received a Section 8 Notice Seeking Posession and have a few queries regarding it's validity. Firstly the Notice has been issued by the 'landlords agent', which is odd as I have always dealt with the landlord directly and this is the first time I have heard anything about an agent. Can a landlord simply assign an agent like this without providing notice that this 3rd party is acting on his behalf? The landlords name and address does not appear on the document at all, I believe it is being done in this way to prevent me from filing a counter claim against the landlord (whose address is unknown) - I can't file a counter claim against the agent as we have no contractual relationship. Secondly the notice claims that rent has not been for August and September. This is untrue August rent was paid but not September, meaning that I am actually only 2 weeks in arrears - if I have understood Sec 8 correctly it requires 2 months of arrears, please correct me if I'm wrong. Is there any penalty for misrepresenting the facts in this way? The reason for September rent being unpaid is that it is being withheld as the landlord is in breach of the tenancy agreement, he was informed that rent would be withheld if he didn't act to remedy this - that issue is a complicated one which I won't go into yet as my first priority is to determine whether this notice has any validity. I have a strong counter claim against the landlord on many points, the most serious of which is failure to carry out gas safety checks and provide a safety certificate for the last 4 years. I fully intend to pursue a claim for compensation against the landlord on a number of grounds which I am confident I will easily win on and believe that withholding rent in lieu is the only way I will see any monies awarded as compensation. I will be very grateful for any advice and opinion people have to offer on this matter.