Question: How to I get a lower intrest rate from my bank for my mortgage?
Answer: The first step is to go to a comparison site as you will need evidence of a better deal than you are currently getting.
Secondly call the lender with the best rate and ask them what are the costs to transfer your current mortgage to them. ask them then to send you an email conforming their rate and costs.
Third when you call you current lender make sure you have all your details on hand so you don't get flustered. There really is no need to put it in writing when your making your initial call to your existing lender as you want to make life as convenient as possible and some lenders will reduce their rates over the phone for you.
Following that you can make a decision to change lenders or just get a reduced rate for your existing lender.