There is not enough information on which to give a reasoned opinion so this is a general reply.
Most insurance policies will have an arbitration clause. This will provide that any dispute between the insurer and the policyholder must be resolved by an arbitrator who is a neutral party.
Arbitration must be sought within a certain time period running from the date of disagreement.
If you do not seek arbitration within the specified time period you may be deemed to have abandoned the claim.
Arbitration costs money.
Alternatively, you could refer the dispute to the Financial Services Ombudsman. Link [broken link removed]
I think that this option does not cost you anything irrespective of the outcome.
Note that the decision of the FSOB is legally binding on both parties.