Window cleaning in Tenements

Does anyone have any suggestions for cleaning the outside of a third floor tenement? We can’t open them fully with our blinds.

My current window cleaner has put their prices up quite substantially and I can’t really afford it anymore. I’ve tried to reduce the frequency but the price has almost doubled for less cleaning. On average how much are people paying? I’m 25 for my third floor getting cleaned every 2 months and although it’s not the worst, my windows are still dirty after they clean (as it’s so high up it’s difficult for them).

I should mention we have five windows (they are quite tall to be fair)