Be clear of what you want.

You want 

1.  refund of mistaken policy premium issued to 6422, because you are 6432 and you didn't get the coverage you paid for. 

2.  compensation of mandatory policy premium purchased by your mortgage company, because the mandatory policy was caused by their mistake.  

There is some overlapping in your demand, probably the true damage was 2-1, i.e. mandatory policy premium - mistaken policy premium.   But you can start by asking for 1 + 2, and end with getting 2-1.