Hate to be the bearer of bad news, but you have a cart that is WAAAY outdated. AND... It looks like you have some custom code that was done for the old site.

  1. Nothing you do to 1.3.7 will help as there are MANY security problems with it.
  2. You need to upgrade to 1.3.9h FIRST, then have someone look at the custom code.

Unfortunately, 1.3.7 is no longer supported and, unless, you can find the original developer for the add-on, you may be SOL there as well.