Flat Roof ... Possible to Recoat ?

Hi. My neighbours got a large flat roof with a typical asphalt roof on it. Anyway it seems to be leaking in a number of places and you can stamp on it, it's bubbled up in a few places and air comes through when you stamp on it.
Is it not possible to roll on some ACRYPOL roofing compound. Is that a good solution, that would be £100. Otherwise it's going to be several grand for a new roof.
Anyone have any experience with that ?
Cheers

Acrypol, cromapol. is a good product for remedial works, if it buys your neighbour more time.

How big is the flat roof?

Thanks for the replies ... apparently they have gone with a new roof.