It looks like you're running in to two different problems.

First it appears that you're getting just a part of a multi-part file. Secondly you're going to need save the parts as binary files I believe.

Something like:

my $num = 0;
binmode; ( Thanks to anonymonk for pointing out my mistake)
open OUTPUT, ">filepart".$num
# print your information here
close OUTPUT;
[download]

As far as putting together multi-part binaries that's beyond my scope, but you're going to need to assemble the parts in order then decode them. CPAN should have the module to do the decoding for you.

Good luck!