Custom Development needed on small website... Current coder unable to do this, and I need postage changes URGENTLY!!

I had a Coder build me a website, then disappear just before finishing. I came back to RAC and got another guy...? However, he is unable to Custom Develop...? ? which is what he tells me I need now. I need a different postage system put in place, as the one the original Coder put in is not doing what I want. Is there anyone out there who can finish this very small job for me???? It is urgent - and needs full attention for half an hour, then we will be done and dusted! Thanks, Guys! Andrea