We sold our house last year. A house two doors up ended up selling for lots less and was on at exactly the same time. The house on the other side of the road sold at around the same time for about £40k more than ours.
The layouts were all the same and I'd argue our kitchen was nicer than the really expensive one. We had totally renovated our house and it was sparkling - every replastered etc... same as the expensive one. You could say they were the same.
But, they had designed it, painted it, staged it etc... in exactly the way people wanted. It was an instagram house.
When we came to sell our house, the EA said make it look like you haven't any children here - despite being a 3 bed house, apparently families were not the target market.
So, we packed everything away the best we could. Took down cutesy pictures, upgraded our toddlers bed to a small double floor bed (which he loved!) and generally made the house as attractive to professionals couples as possible.
But, we didn't go so far as to paint everything in farrow and ball navy and grey though.
Ultimately, we were very happy with the price though we have later on down the line talked about how a lick of different coloured paint could have got us a lot more.
The house two doors up looked like a family home - cot, toys etc... They were a family and it looked like it. It was packed away nicely and everything but they really struggled to sell and had to drop their price. We sold in 8 days - its a very popular road.
My point...absolutely no two properties are the same, even if they have the same layout and general condition, and they are never viewed as such unless they are brand new builds that haven't had their stamp put on them.
If another local flat sold easily and yours isn't selling it is because yours isn't as good as theirs. No one wants to hear that but Rightmove stats say that sales are up by a third in October and that includes flats. Good stuff is selling. Sales timelines are decreasing too; they are faster now than in the summer.
A new EA won't likely help with that - though a lick of paint might.
I do wish you good luck. Apparently flats sell easier in the spring - at least that is what google says. So, maybe its just the wrong time of year. I guess if you're thinking about being inside with lots of friends at Xmas, you aren't thinking about a flat.