I would ring and ask wtf she thinks she's doing; why you are such a low priority for her, what she's going to do about it, and how much she's going to take off your bill.

Sacking your solicitor this late in the day may incur even more delay since your new one will have to go through everything again and may lead to your buyer pulling out. If you're in touch with your buyer, an email expressing your exasperation and explaining what's happened may calm their jitters.