You mention that I should submit a claim to the owner above but also the freeholder (management co.). These are two different sets of people and if you mean the I should contact Mainstay, the management company within 14 days, how will this work if the insurance operated through them stipulates an excess of £5000 which is more than the sum of the repairs (some in estimates only).
You do not answer the question of the excess of £5000 which is operated by the only insurance cover that I have. What is the point of writing to Mainstay the management company when I know what their answer will be?
It seems to me that the only option I have is to write to the owner of the above apartment as you suggest. If I go through the Courts what will this cost and what are the chances of receiving the cost of my repairs by this method. Also this event happened in the city of Birmingham - is the procedure the same as in the Surrey area. The other complication is that the apartments of the above owner will not be permanently occupied and I do not have a permanent address for the owner - i.e. the 14 days grace may not be applicable.