If 3 times decline of credit limit increase will affect the credit score?

I have been using credit card for 8 years. I never once paid any penality for late payment. I always pay in full so never had any 25% interest rate scenario. I don't have any outstanding loans except some installment of remaining about 2k in total for gadgets is being paid monthly. I changed job and the customer service advise me to submit the latest payslip in bank portal to increase the credit limit. I applied 3 times in span of 4 months and it's been declined. I'm worried whether my credit score might drop. I applied for increase in credit limit so I can get a credit card fund transfer of 50% of my limit as one of my colleague suggested more than 50% availing of credit as cash will affect credit score. Any idea on this? What is the best way to increase the credit limit