Please don't let it rain!

So our wiper blades disintegrated on Saturday and it's now Wednesday and we still haven't got a replacement blade for the driver's side wiper! I find it incredible that just getting a basic part is proving so difficult. We had to get hold of the dealership (three phonecalls), they had to order it (24 hours) and they are supposed to deliver it to us tonight (they were supposed to come yesterday but never turned up!). In the meantime we have had to hope it won't rain! How can a company operate like this!