PNC Mortgage No Ethics Internet

I had a mortgage with PNC for 7 years. I never missed a payment and my credit is excellent. I have been trying to refinance with them into a 15 years mortgage for the past three months. They are now offering me a refinance rate of 4% while other lenders are offering me as low as 2.75% refinance rate. Additionally, PNC themselves are offering me 2.75% for a 15 years new purchase mortgage rate. When I asked PNC why the huge difference in rates between their purchase rate and refinance rate, there response was that they artificially inflate the refinance rates due to the large volume of refinance applications, which even if true, is unethical and unprofessional
 
Meanwhile, I think that the real reason PNC is offering me this inflated refinance rate is because they know that that I cant leave PNC for another mortgage Leander because PNC unlike all mortgage lenders or banks keeps refusing to release my SEMA. As a result, if I refinance with another lender, I would have to pay an additional $8,000.00 in closing cost, which makes my refinance not cost effective. Though, while I watch everyone that I know take advantage of the low mortgage refinance rates, I being denied this right and I am being held hostage to PNCs unfair, unethical, and devious practices.