Shorting is very easy with Fidelity. I am surprised it is not just as easy with all the major on-line brokers. For any shorting, you need to have a margin account established number one. Next, since shorting is done on margin, you need to have some quantity of equity in the account to cover the margin. Onde this is established, the process is simple.
I am amazed that you have to call the broker to find out how many shares are available to short, this should be available to you on-line. With Fidelity online, just select “sell short” and select the stock symbol and it automatically pops up a screen that tells you exactly how many shares (if any) are available to short.