Free Initial Air to Air Quote to Replace Gas Boiler

I'm just wondering if this sounds ridiculously oversized, this was a free initial quote from an Octopus trusted partner in my local area and was based on pictures I sent them of my first floor maisonette and all the rooms in it (they haven't come to do a proper survey yet).

For a 61m² first floor maisonette they quoted me £7400 before government grant to replace a gas boiler with a 10KW external unit and 4 internal units (Hitachi of some type, they didn't specify the model) air-to-air heatpump.

Now I don't know much about heatpumps but doesn't this sound ridiculously oversized for a first floor maisonette with a bedroom, office, living room, kitchen, bathroom and landing with a total floor area of 61m²; triple glazing on all the windows at the back, double glazing at the front and good loft insulation with an EPC rating of C and 76 (before the triple glazing was installed)? Is this common practice to send a vague and generic free quote as a first step? Is this reasonable? I'm just trying to work out whether this is decent value or not and appropriate.

I have asked them to consider a cheaper brand like Midea and do I really need 4 units and such a big external unit given only two main rooms need to be above 19C, the rest can be at 18C? No reply yet.