Would you give an LBS your business if this happened to you? I dropped a wheel off on September 17 to have a spoke replaced. I called them today, 9/28, expecting my wheel to be ready. 11 days had passed and they said they could not get the spoke. 11 days to find a spoke, and they never called to let me know. I have found the spoke online in 10 minutes.
Last time I would go there, and AFTER, stress AFTER, I had my wheel back I would express my frustration and let them know I would never be back and advise that I will be passing on the experience. I expect better service from an LBS, that is why I go there and not to a chain, big box etc. for tech work.
Make sure you talk to the owner. I know you don't have to but it may just be people not doing their jobs.
We keep most Mavic spokes in stock. We have had issues getting certain Shimano spokes at times. To the OP, that is a hard one. From the bike shop perspective, it is not ok. If this is not a normal thing with them, maybe it shouldn't decide the whole relationship.
If this is your first bad experience (and you've had several positive prior), then maybe write it off. Other than that, talk to the owner, and tell them your dissatisfaction. Give them the chance to make it right. However, 11 days and no call?...Don't know what they could do to correct this, except a free truing or wheel built (soft dollars).
I waited at 3 months for triple butted alpine III spokes. Unfortunately they never came in. My LBS, who originally recommended to me these spokes, finally built them with what they had in stock. You might ask why triple butted Alpine III but it really doesn't matter. It was what I was paying for. I was pissed just like you. Turns out these spokes are really hard to come by. Think about it before you tell them to go screw.
I do most repairs myself, but when the spoke broke the rim went so far out of true that it wouldn't roll.
A good reason, if you know what part you need, to call ahead and ask if it is in stock. If not, how long until they can get it.