It's not the banks fault that you have a condition which meant their life assurance would not cover you(if my understanding of the orignal posting is correct). This is True that they had nothing to do with me being refused Life Assurance but by law they have to honour it (due to the fact that they used deny people suffering from AIDS mortgages until the consumer credit act was brought in. This was also wrong if a person contracted AIDS from a blood transfusion(i.e no fault of their own ) my condition also occured through no fault of my own.
Nor is it the bank's fault if your engineer filled out the costing incorrectly(this was my own fault hands up but only found out about it after the bank had it for 2 months, very efficient I must say) or if your valuer incorrectly valued the site(it was found later that the valuer actually did value the site etc correctly).
Likewise, if you filled in the paperwork using your wifes married name and she provided ID in her maiden name, (again, that is my understanding of the original post), that is your fault, not the banks (Marriage Cert was sent in with ID documents and they asked me for it again 2 months later and when I indicated this to them it suddenly re appeared). It is your responsibility to ensure that all of these tasks are done correctly and if they are not, any delay lies with yourself and not the bank. If delays have occured as a result and you are out of pocket that is not the banks problem. Based on what you have said in your post, if you had completed the paperwork correctly, none of this would have happened.
Having said that, if the small print says the offer is valid for 6 months and there is no other clause in the agreement allowing them to change the offer, you may have a case for them rescinding the offer, but not for the delays that occured