Mortgage Lending Rates

If I wish to lodge a complaint against my mortgage company which I complain to in England?
My mortgage is fixed now. Bank of England has cut interest rates a record low. I would like to know if the current provider lending rate is consistent with the Bank of England base rate. If so, is there a way I could get out of the fixed mortgage and switch to the standard variable rate. My letter to my current lender has been ignored
Solid say that what you pay no matter how high or low interest rate changes. To change it you will need to re-finance. A variable rate is bad because if interest goes much high, you will have to pay the higher rate.