Bungalow Side Extension Advice

[ryther]

Hi, I'm looking for some advice regarding a detached bungalow side extension.

I have submitted extension plans to the council and received an email recently from a planning officer with the main concern being the extension is too large of a scale and doesn't follow the 2/3 rule in the following guide. The planning officers then gave me an alternative option as shown in green on the diagram below.

The following plans show what a before/after of the property would look like:

Green line = Planning officers alternative

Red line = Ideally proposed

The detached building is an external garage built around 40 years ago with correct planning permission.

I have been messaging the planning officers back and forth and they have made numerous mistakes stating the following:
1. Property's current integrated garage is an extension (False, it is an original feature)
2. Property has two different roof tiles (False, same roof tiles used since original build)
3. Miscalculation of the principal elevation width of the house (out by ~4m)

Each of the above points have been politely corrected and provided sufficient evidence, all of which they accept.

After these corrections, the planning officers remain adamant that their first recommendation still stands, and the extension proposed is too large (despite now using the correct calculation and it being within their 2/3 rule).

The planning officers wont move on the point that the extension can not build towards the detached garage, with the only given reason being its too large in size and scale (For what it's worth noting they did allow for a 30cm increase towards the detached garage).

All of this is slightly confusing and now unsure what is best to do whilst in this stage of "informal" discussions, their original alternative drawing was based on a house which falsely "already had an extension" and was "4m less in width", but nonetheless this recommendation still stands. I have suggested reducing the width, lowering the roof and using a hut style roof for the extension but their heads will not be changed from their original suggestion.

For an idea of the scale of the extension, the proposed extension will have a percentage increase in the floorplan of 44%, and a main reason the owner is wanting to extend is due to the house needing to be more accessible for their disability. There were no objections from neighbours. Is this increase simply too large and unachievable?