Because it's drawing more power than the fuse can handle get a fuse with a higher rating. A 100 app fuse worked great for main power with my setup 760w amp a 15"sub 2 10"subs and a 12" sub. Also my amp had 2 30amp fuses on it one for each channel but I ran everything out of one channel.
Contact where you purchased them from. If they blew with in that short of time it may be user error not hooked up correctly ,wrong impedance, gain to hi on the amp didnt break them in . this will all void any warranty.. .