Wow! I just started using Signs 365 a few months ago and have had beautiful prints and great customer service. I think their prices are more than fair considering the cost of supplies.
Do you have a local sign company that would be willing to work with you?
Best thing to do if you want that fast of turnaround is get your own printer and produce in house. I've used a couple other wholesale to trade and there's still things that happen.... they're just like any other business, machines break, people make mistakes, supplies don't arrive in time. No matter who you go with there's always a gamble.
good luck, I know it can be frustrating.