If your neighbors are unresponsive to your requests, then of course you should call animal control. Do remind them first what the agreement was, since it's been over a month. If they are elderly, they truly could have forgotten. And if their hearing is failing, they may not even be aware there's a problem.
I sincerely hope for your sake that you can get this resolved. I had neighbors who for several years had two labs in a shed facing our house – these dogs barked loudly for hours, day and night. The neighbors denied the barking, even when standing within earshot, they blamed my "nerves" and told me I needed to be on medication, they argued with county officials who were sent out by other neighbors as well, they paid fines, and they determinedly stuck to their guns (literally, they chased my husband off their property once when he went to ask them again for relief). Then budget cuts closed the animal control office, so they didn't even have consequences. I'm a patient and forgiving person, but I truly hope there's a very loud room in hell for people who are so belligerent.
Be aware that there are "silent" noisemakers you can aim at the dog, or even mount on your house, when he's barking. I have yet to talk to anyone who'd used one successfully, but I expect they work for at least some people. Might be a fall-back strategy. Good luck!