1968 LMC Velour Seat Kit Troubles...?

[NJDOTTRUCK]

Have a '68 C-10 with orginal bench seat. The kind with springs and the "thin" foam on top. Bought LMC's "Velour' seat upholstery kit. The seat back part fits great! But the bottom part seems WAY too small. I got it on there, but it's so tight the seams are beginning to split at the lower edges. And the upper front corners are sticking out funny like pleats on a pair of pants. Seems to be not cut right at all. LMC says "Pattern is right/we don't know whats wrong". Has anyone else ever tried this seat kit/have any advice?..