Rent Protection Insurance - Tenant Early Surrender

When there's a fixed term tenancy, and the tenant wish to leave early by offering to surrender their tenancy explicitly or them doing a runner and say "here's the keys", the landlord have two options: 1) say no and let the tenancy runs to the end of its term, possibly leaving the property empty save taking only the necessary action in making sure it's secured; or 2) accept the offer of surrender, with out without agreeing to any extra terms between the parties such as tenant will pay for cost of looking for a new tenant etc., and take possession of the property. If the landlord accept the surrender and take possession of the property, then the tenancy ends, and with it any further rent liabilities.

From what you posted, the insurer is saying you took possession, hence the tenancy ended, there's no further rent liabilities for the tenant, hence nothing for them to pay.