silver65: I am still awaiting hearing from them in response to my 2nd letter (24th August) about all of this but don't hold out much hope.
Was browsing the MS forum and surprise surprise there was an A&L ad for the offer. I clicked away and up until the actual start of the application data entry there is no link or reference to the "no DD" exclusion which as Graeme spotted is ONLY contained at the bottom of several pages of (general) T&C small print not referred to at least in the initial stages of the application.
In fact the offer reaffirms only that "all DDs" need to be switched using the switching service.
In my opinion you have a robust case for the £100 should you wish to remain with the A&L or alternatively an expectation for A&L to arrange the restoration of your previous banking arrangements.
If this had happened to me I would have absolutely no hesitation in invoking the complaints process and on deadlock or after 8 weeks whichever comes first referring the issue to the Financial Ombudsman Service. It would cost you nothing but A&L a hefty case fee regardless of the outcome. It's win/win for you because it will probably take the FOS up to a year to adjudicate, meanwhile you would at least benefit from the other account benefits until another £100 offer comes along elsewhere.
A&L would be daft not to award a £100 ex-gratia payment to avoid the £450 FOS case fee. Unfortunately I cannot say A&L are not daft.
Document the application process before A&L wise-up.