don't have any experience with UB, but my first mortgage was with BoI, I changed there in the last few months and i had several problems with them. There were very quike to give us approval, but from then on therewas loads of niggle bits...because we got our mortgage with the local BoI at home, if we needed to sign any document or get anything changed, you have to go back to the bank you originally got it from, even though you don't live there anymore. I found it very time consuming and some of the trips ended up being a waste and had to go back down again another day..even for mortgage queries you are sent back to your local bank.
I also had another issue on there charging..but thats another issue. I think they over charged, but they don't think they have..when i have more time i'll look into that.