Tried to get "Price Match Guarantee" and got the run around.

I placed an order over the past weekend for a workstation I need for my hobby. The price dropped substantially today and I asked to have my price adjusted. They said their "order modification team" would help in a few hours. Guess what, it's been longer than the promised time so I cancelled the other order and placed another for a huge savings. The problem is, I couldn't use the coupon code I got through my work and it's been a massive headache trying to get this rectified. I'd like the 5% off I get through my work to apply, but no one will help me since it says the coupon has already been used so I just placed the order anyway because I need this PC to do my job.

How can we get this fixed without canceling and replacing a bunch of orders? I want my 5% off, but I was stuck and the order team took too long.