I used to work at Lloyds bank until 2 years ago.
When I started the manager told me that when you do a home ins quote you can disregard 1 previous claim, so if the customer only has 1 claim you can actually give the full no claims discount. I questioned it & called the home insurance department which obviously advised this was mis-information. I have no idea if other areas and managers were advising their staff the same thing but it wouldn't surprise me.
Back when I was there we had a target of 5 home insurance sales a week, Buildings & Contents is classed as 2 sales and the bank was always pushing for more. The branch will have a target of a least 2 Insurance sales a day for a small branch, big branches that target is higher. They even had a league table and prizes for the top home insurances sellers (like any sales role I guess, but home ins was always singled out and selling it made you "great"). If things haven't changed in the last 2 years then you can see why this happens.
Go into branch and lodge the complaint, they won't want it to escalate to the local director and above because it will highlight their mis-selling which will cause the manager a lot of grief. They will likely sort it for you. If the manager doesn't sort it keep pushing because eventually the local director will need to get involved & that's when **** really hits the fan for them. They will do everything in their power to make sure a risk or compliance officer isn't sent to their branch to look through paperwork & question staff on compliant sales