I am flying every year with gear that exceeds the limits way beyond so here are some advices:
First of all if you wish not to pay - do not call them! The operator is picking up your data and may inform the counter attendants so they can be prepared and there will be no escape! Everything is written on the website of the airline.
Second, at the airport and if there are more counters open for your flight, make a choice - rule 1: If you are a man go to a woman attendant and viceversa; 2 rule: Pick up the one that is in good mood and smiling - she/he is the one that will just forget about policy; 3 rule: make sure you are not late and stay on the line so that a lot of people are behind you - this way the attendant will be busy and under pressure - so less prone to delay so many people with your problem!
At the counter: Be cool and smily, try to make good impression and don't be nervous - act as if your luggage was just normal. When they are weihging it, don't put it full lenght on the line - this way they will not see the real size and weight. You can also hold it with your hand on the handle at the top of your golf bag so weight will be minimized even more
If all of this doesn't work, have a plan B with super cool explanation. Hope you will succeed because plan C is a scandal in front of the crowd hahahahahahha
Few flight attendants are tough enough to go throuh all of this but still there is a chance you will have to pay them. Otherwise it feels so good going to the gate