Our house is covered by separate insurance policies for buildings and contents. After a storm, the buildings insurers paid out on a claim for missing roof tiles, but the contents insurers refused to pay for damage to a carpet caused by water coming in under the patio doors. I feel the damage must have been covered by one or the other!
You’re generally advised to take out buildings and contents insurance with the same firm to avoid just this predicament. Your two firms will have internal appeals procedures you can go through, and will probably also be members of the insurance ombudsman scheme if you can’t resolve the matter. It could be that your claim has been rejected because the doors are badly designed or fitted, but without looking at your policy schedules in detail it’s impossible to say for certain.