Household & individuals - Direct debit problem

We are setting up pledges for FY 2017/18 - we have a problem with one constituent's account - despite setting up the pledge on the individual account - which is necessary as that is where the direct debit information is, and of course the matching constituent ID for the claim - Tessitura is defaulting to the household account - where there is no direct debit information. On trying to delete the household account we are getting a message "Cannot delete affiliation because one or more affiliate is depending on the Group for the Primary Address. The rule for Require Address is turned on, which enforces a Constituent to have at least one Primary Address (Constituent Address)". As far as I can see, they both have Primary addresses - can anyone tell me how we can get round this - otherwise we will have to send a new REC DDI - which we would rather not do. Many thanks Eleanor Roberts (Halle Development)