@funnybunny:
The springer owner immediately starts yelling and screaming loudly, iam already there on hand but after several times like this during a month she is ready to report me.
It seems our time could be clashing a- The lady is not very firendly as it is, and i dotn think she will be willing to co-operate with me- "put you dog on a *****ing leash when im here."
Unfortunately, as you are the one with the dog that is being aggressive, it is up to you to avoid confrontations (as you are doing). If this snarkiness should degenerate into an actual fight, it would not be good news. If you are going to try the muzzle, best to give it a go at home. He will likely hate it and try to get it off, so make sure it is adjusted in a way that he can't do that. A box muzzle might be a better answer, someone with more experience in this area will hopefully respond.
It's funny how some dogs just take a dislike to a certain dog (and may generalize the dislike to all of that breed), but it's important to pay close attention in case he decides to get tough with others that he has previously gotten along with. A check of his thyroid levels might be a good idea.
Since I have been on both sides of this situation at times, I can tell you it is no picnic to have someone else's dog pick on yours. You may feel the lady is being unreasonable, but until you have walked in her shoes I wouldn't be too quick to judge. I've had a dog of mine attacked, and as a result. I will do whatever it takes to deter an aggressor. If it gets hurt in the process, so be it. IMO, a dog should be under control of the owner at all times. If the owner does not have control, the dog should not be loose. You should be able to recall your dog, even with major distractions. Not easy with a Basenji, I know, and generally impossible once a fight has actually started.