Leak around soil stack

[LeakyRoof]

Hello folks hope someone may be able to advice, we have a very bad leak on a flat roof, the roof is felt with a soil stack going around it, the stack has never had a collar, I'm not sure how i can seal around this, the pipe seems to be metal and goes all the way upto the bathroom and then up into the main roof, can't see any way to slide a collar over it.. the pipe is also very close to the wall and everytime it rains it just pours through the roof.
I've tried using flashing tape to tape around it however its not sticking very well and its hard to do as its so close to the wall, just wondering if there is anything that can go on it, sorry havent got any pictures, didn't take any when I climbed up to wrap the tape

 

[Nige F]

Try wrapping with old fashioned Denso tape - wear gloves

 

[LeakyRoof]

Any of these it please?
https://www.screwfix.com/search?search=Denso+tape

I used flashband tape by evo stick I think and that didn't stick

 

[Nige F]

No it's not on Screwfix site. Put Denso Tape into google I saw it on Amazon and Travis Perkins builders merchant. May also be at plumbers merchants.

 

[catlad]

Just dump a tin of acropol over the effected area.

 

[CBW]

Sand and cement mix? Photo of said pipe?