Letting Agent in breach of contract with Landlord or not

I am terminating my Letting agent as with their terms of contract ie 3 months notice etc but they are still arguing adout finishing date.
I think the Agent has been in breach of contract for the following reasons.

  1. Failure to give me the chance to supply and fit new smoke/carbon
    alarm. Agent supplied and fitted with extortionate bill taken out of monthly rent (no receipts). As outlined in Landlord Information pack the Landlord is responsible for the maintenance of the property not the Agent.
  2. In your email 13th March 2024 you stated that.
    When there was aTransfer of Ownership to my daughter we
    were assured that other than a name change the original contract signed by me would remain the same.
    The Agent assured me and my daughter that their fees would remain as per the contract originally signed. Its also in writing.
    On transfering the ownership their Management fees went from 5% as
    original contract to 7% without any notice whatsoever.
    This was queried at the time no response.
    Are they in breach or not it makes a difference to the termination