The function of the gallbladder is to process the cholesterol that you consume in your diet. This means you have too fatty of a diet. So, obviously, you need to change your diet whether you have the surgery or not. Avoid fatty foods, simple. Think about what dissolves or "cuts" the fat - lemon juice. So, drink lots of hot tea with plenty of lemon. Or just drink hot lemon water with honey to sweeten. You also need to exercise more so that the fat you do ingest has somewhere to go instead of your gallbladder and liver.
If you have the surgery, your liver will eventually take over the function of the gallbladder in processing and removing excess cholesterol from the bloodstream. However, if you don't change your diet, you will put further hardship on your liver and your heart, requiring medicine down the road, which has its own side effects.
If you can avoid surgery, that is the best solution, as the body was designed to keep all its internal organs.
If you don't have the surgery, a stone could get lodged in a bile duct, causing the worst severe pain you could imagine. This requires immediate surgery as you will have serious problems if the gall bladder bursts.
So, a suggestion would be to schedule the surgery, but while you are waiting for the surgery, say two weeks later, change your diet and begin to exercise. If the pain goes away and you begin to feel better, then cancel the surgery. The doctor knows all this other stuff, but they don't tell you because you didn't know to ask him. Besides, if he tells you this stuff, he can't pay off his BMW.